I lived in Lubbock, Texas for nearly 10 years back in the early 2000's. My neighbor was a retired Texas Tech physics professor who had built a thermal battery in his garage. At first when I heard of a thermal battery I laughed. What for and why?! George, my neighbor, was more than happy to explain. He proceeded to explain that his ~600' of 3/8" black UV resistant tubing in a long box frame (~12' by 6') produced boiling hot water in a few hours each day. He had a 300 gallon stainless steel insulated container on a legs with a few different pumps and lines going out. One went to his jacuzzi, another to his hot water heater (or preheater), and another to a garage heater. During the summer, he hardly ever turned it on, but from late October until March we'd see billows of steam rising from his back yard when he took off the jacuzzi lid. It could be 40 degrees outside and you could hear the stainless steel container bubbling with what I assumed was boiling water. I know you could feel the heat when you stood next to it. George taught me a lot about physics over the years. He passed in March. Thank you ol' buddy for all the knowledge.
George sounds like an awesome person! I live in Bangalore, India, which apparently has the highest number of solar (thermal) hot water rooftop installations in the world! I'm pretty sure we've had one (or two) in every home I've lived in, atleast for the last 2 decades. One of those things that you use every day, but never notice. I can't remember a day when we didn't have hot water!! There were days without water, at all, but we always had hot water 😂😂
in Syria, every house or apartment has thermal solar panels. They are amazing and work very reliable. And no, we don't use pumps, if the house is not very high. Close to the panels we have an isolated tank, which get filled by the water pressure of the grid. Then the water gets heated and the gravity does the job delivering it to your house. And yes, even in the winter when the sun comes out, we get good warm water. It is the best investment a house owner should do.
I really wish I had a teacher like you at any point of my education. You're so articulate down to point of complete understanding. It's beautiful... thank you for the videos.
… the Beaty is, that your education is still incomplete and through the power of the Internet he is your teacher! You just learned by watching the video!
I discovered your channel a few weeks ago and I will be honest. You rekindled my love for science. I have not seen anyone explain things the way you do. Thank you for doing what you do.
@@TechIngredients Agreed. You have an excellent and thorough approach. Questions on this project: I know radiant floor systems recomends PEX AL PEX to stop oxygen ingress and therefore corrosion building up in the system. Can you comment on that and lifespan of this system?
@@TechIngredients One other question: Could you explain why setting the coil into a block of black pigmented concrete would be inferior? It seems that it would be a lot more resilient than glass and provide better protection for the PEX; especially from long term UV damage.
It's possible to enclose the back of the PV panel and run water through the back of it as a cooling jacket. This means you heat water, generate electricity and keep the panel cool which boosts its efficiency. Would be great to see you attempt something like that.
Also think this would be an interesting experiment though i think it would have already been a product if cost, efficiency and reliability were reasonable.
When I was in high school, we had two vakuum tube water heating panels on our roof in Germany. This was a great investment as is, but it became especially clear in a year when both my parents were unemployed and we could not afford fuel for the heating system. These two panels allowed a familiy of five to take luke warm showers throughout the Winter.
@@eyeballengineering7007 only if you've got enough of them though! You'd need several times the area of the thermal system - double the area at least, just to reach lukewarm. A more efficient method would be to use a combination of the two, with the PV array powering a heat pump, to concentrate the sparse energy from the thermal system down into a smaller volume of hotter water.
@@eyeballengineering7007 Note that this was 20 years ago. The system was quite complex with heat storage tank, and excess heat radiator, multiple electronic valves, etc. Also the people who installed it did not make sure that the metals of the different lines are compatible with eachother, which lead to an expensive renovation, but that is just bad craftsmanship. Today it would probably be easier to use PV panels and a heat pump. You probably still need the heat storage, because battery storage for heating is still expensive.
I try playing these videos in the background while I'm doing other things, but your explanations are so thorough and technical that it becomes nearly impossible to follow without giving it my full attention. The cognitive nutritional density of your videos is second to none on this platform.
I've seen the use of electric water heaters as overload devices for DIY water turbines in off grid situations. Which is a cool way to store or use what would otherwise be wasted.
Also in wind turbine it's common to have dump resistor that slows down the turbine if there is no other load (batteries are fully charged or something). And the dumo resistor can be water heater.
Seems like if you finish heating the water then put excess energy into pumping water up to a higher elevation. Then it can be a circular system, you won’t have to pump as much water to keep pressure in times of peak/excess energy so it would be a great time to take a hot shower! Just like with rainwater harvesting but with electricity.
Energy storage to a heat sump is an excellent way to store energy you don't have an immediate use for. Still your first choice should be an intelligent / programable electrical load management system. It requires rethinking the way most of us use energy in our homes. A well thought out system can minimize the maximum production capacity of your system and save you a lot of up front money. Which is what I've always thought was the most attractive reasons for an electric vehicle. Make your own transportation energy and get off the gasoline price roller coaster.
As an EE, I really enjoy your work and that of Ben at Applied Science for my continuing education. No One of us knows it all but we can all press on and continue to learn. THANK YOU for your contributions in science and your empirical research which you share with all of us !!
@@TechIngredients I have an idea .. Will need a bit of thinking .. You can use a pinned comment.. As there are 2.4k comments.. it's a lot to wade through.. It could be used for comments to improve or modify what your video is about... I don't remember seeing... Have you done a video about using those ceramic resistors? and how to calculate the Actual resistance? What I would really like to know is a way of doing a cost effective and affordable electronic PV dump load circuit.. maybe in incremental stages and making the water heater element, from resistors and resistance wire.. apparently some say use mains voltage ones but I'm not sure.. ... Back to feedback idea.. and do follow up video thanking and explaining them .. a winter task..? I'm been living off grid over 33 years .. Low budget, no subsidies etc.. I've still got the decades old little glass panels.. I'm in the process of setting up a TH-cam channel.. this has made me think I should film and talk about the early days of those panels... they were expensive but were worth it to not hear the engine or generator running.. I live on a Boat .. monetary or environment were in mind.. my sanity and to hear the birds not coughing was uppermost.. Thank you for your channel and in part making me realise I should do a channel.. Maybe you can inspire others to do a channel of what they have done.. the more this is normalised the quicker the reduction in planetary damage... I liked you saying about subsidies etc.. UK gov keeps giving £b to rich people here.. that makes them £s and they don't pay it back..... You made me laugh about cursing the universe... Sorry bit long comment.. hope of use... Kindest regards Mark and Bella...
What is News most people in the know already aware of that But they also know that to much hot water can be a major embarrassment where as surplus electrons can be shed to the grid or otherwise dumped
@Tech ingredients is it possible to use this hot water to generate electricity with a stirling engine?? I wonder what efficiency gains it might have over PV. Also, Stirling with solar heating is definitely cheaper than PV.
@@gauravsarraf So you are touching on the holy grail of energy harvesting. Thermal Energy (say Joule or BTU) is more useful when it's at a higher temperature. Recovering energy from low temperature heat sources (like 20 or 30 deg C) is generally not economical. If it was, oh boy! Sterling engines, Organic Rankine cycle, thermoelectric devices all work at fairly high temperatures (relative to 30 deg C). I'd love to see the creative ideas that come out of a build to optimized energy recovery from a 30 deg C heat source.
I live in VietNam few degrees north of the Equator where we have a 6 distinct ethnic groups many of which live in reservations or defined areas. The Government of Vietnam has done much to promote these groups. Using this excellent video, a group of us have sponsored and built several systems in different parts of the country providing hot water and electricity. A couple of projects were large water capacity and smaller electrical systems whereby a group considered water to be the more beneficial. The small electrical system is used to power water well pumps. This series is so helpful in 2 ways: education and practical use. Thank you so much.
I built a similar solar water heater for my outdoor shower using about 12 feet of 4 inch black PVC pipe. It provides hot water in the Pacific Northwest from March to October, and worked very, very well, to the point I had to caution people about the need to mix cold BEFORE getting in the shower. Adding a glass cover made it too efficient, and the high temperatures melted the PVC joints enough that they popped off from the pressure. Thanks for the video!
Now that's a sentence you won't hear often ,,too efficient" . Awesome Copper tubes with those crimp joints should Work. If you use a sooty flame (Carbon Nanotubes) to make the Copper tubes black it should be even more efficient due to copper and Carbon Nanotubes transmitting heat 1000x that of PVC
I have been working on adding cooling to the back of solar panels to cool them, hopefully to raise their efficiency on hot days as well as prolonging their life. The cooling will also provide pre-heating for my hot water heater and/or my pool. I’m also going to try to cool my house in the summer by cooling the house by running pool water through a forced air radiator in my house.
@@xmtxx, I came upon the idea and developed some approaches. then, I thought to look and see if anyone else had the same idea. I found a few people who had done it or at least researched it and proposed methods. Now, with bifacial panels that already have two sealed surfaces, it would be as easy as designing and bonding a cooling circuit to the back… I’m working on one that bonds “U” shaped circuitous channels to the bottom glass. This would couple the water/coolant directly to the glass, as the cap on the “U” channels, making them tubes
Hey! Were currently building our house and would be really interested if you have any designs or links you are willing to share? 😊 Totally understand if not though. Thanks.
They do exist commercially, often under the term "hybrid solar panels", although they don't have a huge market segment. I think one of the big barriers to adoption is that you need an installer who can handle both the electric and plumbing work, and it needs to be integrated both into the electric with an inverer, and the hot water system, which increases the cost at time of installation. I also don't think there's as many people/companies doing it, which also makes it harder to get right now.
Cool idea. Are there submersible PV panels? Would be cool to see how water depth over a PV panel affects efficiency. Would be cooler to see if that efficiency loss can be made up from extracting heat from the PV panels.
When I lived in Turkey these solar water heaters were very common, and in Alanya where I lived I only had about a week per year when the water was lukewarm the rest of the year the water was burning hot, a really great money saver.
This panel can put out close to 100 watts th-cam.com/users/postUgkxOqI2yqX0XVrhR2BMJciTWrHJpG8FhJyg when positioned in the appropriate southernly direction, tilted to the optimal angle for your latitude/date, and connected to a higher capacity device than a 500. The built in kickstand angle is a fixed at 50 degrees. Up to 20% more power can be output by selecting the actual date and latitude optimal angle.The 500 will only input 3.5A maximum at 18 volts for 63 watts. Some of the excess power from the panel can be fed into a USB battery bank, charged directly from the panel while also charging a 500. This will allow you to harvest as much as 63 + 15 = 78 watts.If this panel is used to charge a larger device, such as the power station, then its full output potential can be realized.
Solar water heaters are great for purposes like heating a pool or a camp shower, but what would it take to actually pipe the warmed water into a standard home water system? I suppose you would just pipe it in line after the hot water split off before entering your water heater? A relitive of mine has a commercially made solar pool heater that uses what looks like a heavy duty version of black coroplast. A pump feeds water up onto the roof, and it then gravity feeds through the corrugations in the plastic sheet and down into the pool. I thought that was a pretty clever idea to get a huge surface area with a fraction of the material as a spool of pipe.
I have a commercial solar water heater at home with about 1.5x the size of the one in the video: it uses a separate water circuit to collect the heat and then transfer it to or rather share with the hot water circuit/boiler of the home. becomes ultra hot in summer! In winter, it is pretty much useless, as he said in the video
We use a heat collector thing and we have a tank in the cellar and I think there is a spiral in there that heats the water in the tank, it's not water that is getting heated in our system but glycol I think. In summer we usually reach like 100°C on the roof and end up with like 80-90°C in the tanks and that is plenty for showering and stuff like that
its generally not hard at all, you usually have a heat sink / exchanger before your hot water heater. they are just a water tank with a coil in them to pre heat the water before it gets to the water heater.
It would be really interesting to compare the resistive heating used in this video with a more efficient mechanism like a heat pump to see if that arrangement would outperform so direct solar heating. As far as I know a heat pump should be at least twice that efficient than resistive heating. Great video overall! Enjoyed watching it
there is also geothermal heat pumps that have a Coefficient Of Power (COP) of >4. what if you combine both of them tho. PV to power the heat pump, and solar water heater to heat the coolant circulating through the heat pump. this would maximize the heating ability of the solar water heater as well given there is a greater temperature differential
@@Cracked1ce Sounds like good ideas for future projects and videos. The guy in this video does a great job of being fair and explaining the actual real costs. Not some fake sales pitch. Also disclosing the issues of tax credits. Is it fair that someone that can afford a new car can buy an electric car and get a 7,500 dollar tax credit? Can someone making a mid to low wage afford new cars? even low end EVs 40,000 .
Keep in mind, that adding a heatpump to the PV Array will increase the costs dramatically. So you should also expand the solar water heater Array to even out these additional costs. Than you should compare the outcome. And I think, you can easily quadruple the solar water heater array for the cost of a heatpump.
But that isn't an apples to apples comparison. The heat pump is capturing heat from the air which got hot because of the sun hitting the entire region of the country. The solar water heater is capturing heat from the sun that hit the box.
Was actually expecting a higher difference in temperature due to the inefficiency of PV. What id love to see is what happens if you leaverage the benifit of generating electric energy rather than heat energy, by for example using a heat pump rather than just "burning" the electricity. This would also allow for other sources of electrical energy like wind and water power to be used more efficiently. Also i think it is worth taking into consideration what happens once your water is heated. Especially thinking about seasonal storage here. Id love to see a future where we use the energy generated during summer to produce synthetic fuels that we can store and use to heat our homes in Winter
I strongly second this. Most air conditioners have COP of 2.3 to 3.5 (Wikipedia), meaning that you can expect up to 3.5 times the heating that you would from resistive heating as was done in this experiment. If I had to future-proof, I'd also take into account the flexibility of electricity and the forcing function globally for improved heat pumps and more efficient PV. Solar water heating, as efficient as it is, could not be expected to improve much. I'd rather invest in infrastructure for the former, even at a greater initial capex.
I had just found your channel and wanted to say that I appreciate the way you explain the reasoning behind a choice and the technical side of what is being discussed. No hand waving or not going into detail. I very much so appreciate that.
Basically "Every energy conversion comes with a loss, so less of them = more efficient system" Episode 2137 But it's only true if you're using that electricity to generate heat. It's not popular but I've seen homes with both systems. Collector for heating up water (or helping heating entire house in the season) and next to it PV for electricity production (for light, fridge and so on)
Excellent presentation. Very informative. I use solar panels to heat my water. I have dedicated 5.6 kW of panel's just to a large storage tank of 315 litres. I rely on the size of the tank to offset cloudy days of low output. It's not a perfect system but it's free hot water. I did consider a solar heater but roof space is not an issue and plumbing I prefer to keep to a minimum. I am a great believer in oversizing solar strings to offset low insolation day's.
Thanks for using clear, objective english. I work with a painter, and first job of the day is putting a 5gal bucket of water outside in the sun. By days end, we have steaming water to clean the brushes. I use the dashboard of my car to heat my lunch. It's a natural microwave. With me, you're preaching to the choir. All the same, keep the vids coming.👍
The system I'm currently designing for my house; involves a solar thermal loop, an insulated energy store.... and converting the heat to higher quality by use of a heat pump (powered by solar PV). As the heat source is above ambient, the expected COP should be far better than other heat pump solutions.
how does that compare to freeze storage systems (systems that take the heat from freezing the water) I am wondering if it would be suitable to utilize the heat from a solar thermal panel to remelt the frozen store during the day.
The issue is with usable heat - on a sunny day, the same area of solar thermal would deliver more heat than necessary, but on less sunny days thermal alone can't create hot enough water for domestic use. The water from the thermal store isn't used directly (which avoids the complications of heat cycling sterilization) instead, the heat pump creates hot water on demand and can run from the grid (which in my locale is wind generation dominated).
@@DT-dc4br do you only mean hot water or heating. 🙈 maybe i have got you wrong. i was referring to heating, for which no sanitization would be required. I meant that a store doesn't need to be hot but can be just cold water and the heat pump can extract the heating from the freezing water in the store ... the store would be underground and otherwise unisolated and except sludge I don't see why it couldn't be open for external water. it's a concept sometimes used here in Germany (called "eisspeicher") ... anyway i still am not sure how to reliably turn the ice back into water for the next night except naturally melting. solar may be a suitable low energy option to supplement this. clarification: on our property there is already a water store that has been used differently in the past. however it is a little bit smaller and shallower than required so i would need to utilize it outside the bounds for a proper ice/freezing store and thus for very cold nights need a way of melting it back during the day... .
@@CM-mo7mv Both space heating and hot water from the faucet. If it's just for space heating, then lower temperature water can be used with larger radiators or underfloor heating...but then again, for most of the summer months when the system is getting the most energy... there's not really a requirement for it.
@@DT-dc4br absolutely ... that's why i am referring to winter and colder months ... I don't know which climate you are in but if it is anything like in Germany with sometimes quite chilly winters looking into differentiation in space heating and faucet heating.... for the later i calculated it may not even be worth it to have centralized faucet water heating as the power needed for that and much higher temperatures to be up to code plus the return path and capacity for higher demand ( e.g. taking a bath) results in almost the same amounts of power needed than full electric on our usage pattern and structure ... however i did not calculate with added solar heat during summer time yet (thanks for that pointer)
I got really into this a while ago and did some research on it. There were a few things that made me decide PV was the way to go. #1. You use heat pumps to heat not resistors. So you can get a LOT more efficiency out of modern heat pumps & these things are going to be very reliable if you want to be able to occasionally use the grid to power water heating in the winter etc. #2. You mention some of this at the end, but complexity in the solar heat collector for dealing with freezing and something you didnt mention - over heating. Over heating can be a big deal if you arent drawing the heat out for a few days during periods with a lot of sun. Industrial systems have pretty extensive solutions to deal with this that would add some cost to a home system if implemented. There was a great article i read summarizing all this too - if yall are interested i can try to dig it up.
Yeah I had all materials to diy a thermal heater, but freeze, over heat, and a lot of potential leaking made me decide solar electric was more practical.
A DIY over-heating solution shouldn't be to difficult. Just a thermistor, two electric valves and a microcontroller. And anti-freezen should prevent freezing, shouldn't it?
@@Jehty_ Yeah you need to vent it if it over heats, and I think you need to vent it near the top of the whole assembly. If you use anti freeze, you also will need a heat exchanger to move the heat from the antifreeze solution to your house water. These problems are certain solvable, but they add cost and maintence issues, and you might not want cheap DIY things for a house you may sell... now that all might be fine but... When you factor in the heat pump hooked up to PV giving you 2-3x the amount of heat generation as a simple heating element... PV really just makes a lot more sense.
Ive been building my own insulated panels for the last week now, heres to hoping they work in -25c. Wish there was a good way to share the progress on them. Either way its nice to see a scientific approach to showing the differences on many different aspects of what is truly a simple yet affective technology. Great video and look forward to more.
There is no reason that solar won't work at -25C, however here on Earth, in practical terms, that likely means besides cold temperatures, you likely also have low solar insolation (sunlight).
There are a few things I would love to see you test out. 1. Vacuum tube glass that is tinted dark or a beer/soda can heater. Both of these options are similar to your coiled pex tubing but I've seen them get extremely hot and move air using a 12v pc fan with a solar panel. I've even seen the glass vacuum tubing marketed as a solar cooker. Another thing I've seen is what's called a passive wall. Maybe not build it on your main home, but if you have a non powered shed that you work in, pick the side that gets the most sun during the winter and build a transparent box thats as air tight u can make it using greenhouse plastic tiles that look like metal roof tiles, on the outside and dark paint underneath. Inside this box cut vents along the top and bottom of the structure, protect it from critters with metal mesh and put one way air valves (like a piece of tar paper, cork or even adjustable dampers that flap one way only.) that lead inside the building, and on the bottom have it lead out to the greenhouse. The enclosed wall box would create a greenhouse effect and also generate pressure with the hot air that would blow into the building via expansion. As the air cools it gets sucked back out into the greenhouse wall and expansion occurs on a cycle. I've seen one person do this before on YT but you have a better channel to measure and collect data. Passive systems are the best systems!
That is a version of Trombe wall. If the back of the box has high thermal mass (such as a brick wall) it can help keep the building warm into the night.
It would be really interesting if you ran the test with data logging, so we could see the water panel's efficiency drop as it heats up and at what point it becomes significant.
I think this would be the case with both... As the panels reach their max output the power curve will have a similar shape. But even more interesting would be if you had the data and could take the area of both curves to find the total power output of both and how they compare.
@@pietersmit621 But it is effected by the temperature of the panel itself. I don't think it would be to the degree that the water heater's efficiency drops as it reaches it's peak though. Two different physics involved there. Still, there's a lot of data to consider there, with more instrumentation of course.
@@trplankowner3323 not just the temperature of the panels also the temperature of the resistors. these will increase in resistance as they heat up. this will lower the current draw and therefor make the panels less efficient as they are not in there optimal current output anymore. its one of the reasons why MPPT chargers are better than PWM ones. the MPPT changes its charge rate based on the optimal current draw from the panels
@@justingort1 While all of that is absolutely true and pertinent in certain perspectives. That isn't what I was referring to, I was agreeing that more data could be useful on this comparison. There's so many different aspects involved in this test that many could spend weeks or even months delving into the details. On each system. Still I think that the gross point of the comparison remains and is valid, much more energy is gathered by the hot water collector. However, if you need electricity and not heat, short of building a greatly more intricate system, stick with the PV panels!
The Copper would conduct the energy at a greater speed than the Pex. However, since a therm of energy is permanent, it is going to move from high energy to low energy fairly efficiently. It won't simply disappear. The cost today of 200" of 1/2 inch copper tubing is around 750.00. The cost of the same length of Pex is around 105.00. Huge cost difference. And unless you require an instant heat, the added cost would be unnecessary because, the heat will find it's way into the pex. My garden hose laying on the ground gets hot enough to burn me when I first turn the water on. And, that's with no thermal glass, no box.
@@SUPERMAKFISH for sure a house can be super hot and less costy if you store some thermal activity in good sealed tanks!!!! my next project!!!!! but not before instal some off grid electricity backup storage
Having lived off grid in remote wilderness (Almost 8 years) I have some thing to add to the comparison. The hot water is plentiful in the summer but in the north where we have long cold winters, -47c only the Solar panels produce and they do so with easily as the lower the temp the more efficient they are. It all boils down to where you live and the weather you have. I Still go Solar year round..
That's my plan for the farm here in central Manitoba. Solar pv panels all year round. Hot water collectors in the warm months & wood heat in the winter. And wood fired water heating in the winter. Which helps heat the house.
@@larryrobertstein7485 That is way to do it. I never was in a power outage because I had my own , just do 2 things, live within or below the power output of your solar system and keep the batteries from freezing( a fully charged battery will not freeze) my dad had a farm outside of Ericksdale Manitoba , small world.
This somewhat illustrates the difference between the theoretical and the practical. Starting in the late 80s and early 90s, various neighbors of mine began installing solar hot-water systems of this type while others began installing PV systems. Not one of the hot-water systems in my neighborhood is still in use because they always had maintenance issues and required monitoring and attention. The last one that I saw taken out was because a buyer of that house required its removal as a condition of sale. I have not seen that happen with PV. Most of the PV systems are still sitting here (often with a set of replacement panels) because they are very simple and reliable with little maintenance or further investment of time or money required until decades later when the panels are no longer producing sufficiently useful power.
THANK YOU, that is what i see all over here around me too; i am in Porto, Portugal ( that poor place where the INjustice system sucks big time, ask me how i know ); from my roof i have a clear view with binoculars of some 60 roofs at the same angle, and 15 years ago there were 10 or 15 hot water panels on them, and about 10 electrical PV panels; today i see only 3 hot water ones but 23 PV ones; my PV panels are about 10 years old,they have been performing great, no breakdowns at all,apart from the occasional inverter failure; luckily i can build them,and so,i have them modified to use main ICs in boards in sockets and it's just a matter of pulling one out and pushing a new one in,once every 2 or 3 years, they only cost 3 or 4 euros each,delivered from china;they are the famous SG3525+LM358 board for the first stage to get 380VDC, and the EGS002 board for the second stage to get 220VAC 50hz; coupled with the Lifepo4 batteries they run the whole house,not just the hot water; Solar panels never breakdown, i never heard one one failing,it's just amazing,they last 20 or 25 years without fail; inverters are another story,but i use the cheap 150 euro chinese ones,they say 5000 watts,but they are good for 2500w all day; their 16 mosfets and their 4 IGBTs never braek down,it's the smaller boards,the control board ICs, that fail,and theey were sanded down by the maker,so i can´t replace them; i now have 1 more new second stage unit ,an open unit,no box,no volt meters, of 3000 W or more continuous, a small monster with 8 IGBTS, that only cost me 52 euros delivered,and it uses the EGS002 board of which i have a few in stock, but this thing is so over sized that it probably will last a long time; i get 2000 watts max (that is 200WH of elec juice every hour!!) from the Sun,from my 8 older panels,plenty in the summer,not enough in cloudy or winter days, when they only deliver 100 or 200,sometimes 50W and less; of course, near ZERO at night; I'd rather deal with wires than with pipes thru the house, and most of the wiring was already there; and again, with a proper MPPT,LifePo4s,and inverters, PVs run the whole house from the whole March until the end of October; and some days in winter too at least partially; I have a 24 volt system,i started small,less batteries, pity, should have been a 48 V volt; 24 V are good only up to 3000 watts max,and they require heavier wires that 48 volts too.
@@notajalapeno4442 Yes and no. The usual dud shemesh is still maintenance-intensive compared to PV, and it does not get nearly as cold there as in much of the US and northwestern Europe, which adds to the design complexity for deep-freeze protection and therefore more maintenance. Even in Israel, they have to have a variable supplementation system in winter in almost every application, which is more complex than just plugging PV into an existing electrical panel.
Before watching: absolutely a Thermal Hot water heater is generally far more "efficient" than Solar PV (as long as you want hot water, the energy source is much less convertible) It is cool how the e-glass acts like a thermal "laser-like" amplifier However on a cloudy day, its output drops to "zero" - well lets call it ambient, no gain. Our hot water heater gives "free" - (Cost well and truly offset) hot water for 90% of the year, by Solar PV, offsets the rest of the power we use (Cash Positive).
@@garethbaus5471 : yes indeed, I haven't tested if the pump gain will make it as "efficient" as the hot water heater (a lot more complicated).... As previously stated, convertibility and tradability of electricity is the major benefit of PV... Also, the high price of Commercial Solar hot water heaters pretty much make them unattractive to install these days (PV plus heatpump hotwater heaters are most likely a better "financial" decision). Next for TI to show home grown PV storage for flexible dispatch.
Keep in mind for the taxes, that solar panels would likely be more competitive without tax subsidies & incentives if gas and oil hadn't received many such subsidies as well (or at least received them in the past, furthering their development and infrastructure). I agree though and think we should get rid of all of them rather than fight fire with fire. Very cool video! I'm really looking forward to more! I also agree with other commenters that I'd love to see a hybrid panel which uses the fluid to cool the PV panel
Thank goodness for oil. As we can not live without it. All you do, eat, sleep, medication, products, cars, and whatever is thanks to oil. This is something the oil haters forget.
Europe hasn't had any incentive on oil and gas for decades. Last time there was anything like that was in the 70's with the energy crysis. Solar panels still only make sense because of heavy subsidies. I'd love for renewable energy to become viable. I mean it's free energy for crying out loud. But they aren't there yet. Nor is there any sign that they'll be ready by the time politicians want to phase out fossil fuels. It's foolish to preach for the phaseout of fossil fuel before we find a suitable replacement. Which to be fair nuclear power would be a more than capable replacement but if people don't want to use it then we'll have to wait for something else to be developed/perfected
@@tfwmemedumpster Oil and gas is renewable, it a mineral that regenerates from subsurface pressure of carbon and hydrogen (organic compounds only means it has carbon it in) this happens under ground to form complex hydrocarbons, before we started harvesting oil, oil would literally flow up naturally out of the ground.
it's less that oil and gas have been subsidized, which they have in some countries (read: globalization incentivizing oil and gas), and more that oil and gas companies can outsource costs onto the public. The cost of climate change is something that can be outsourced, the cost of people dying from lung cancer, because they lived too close to the coal plant, that's a cost that's outsourced. The incentivization of solar is meant as a way to combat the outsourcing, the "hidden costs", carbon tax is a way to combat global oil incentives.
An enjoyably informative video as per usual! Just one thing: The PV panel table was slightly lopsided --- away from the sun --- perhaps reducing a few watts. That said, producing heat from sunlight is easier than producing electricity. In equatorial regions, it's quite possible to even use the heat so collected to drive a steam turbine (I've read of and seen videos of companies doing this in places like the Middle East). But, for most places and especially in the upper latitudes, having both PV and heat collectors is best --- heat collectors for heating and PV for electricity (which can also be used to drive the pump in the heat collector).
My mother installed a solar water heater on her house in Arizona about 1975. It did an amazing job of keeping HOT water. She considered also expanding it to keep the house warm in the winter, but the cost of plumbing the house and a radiator in each room was prohibitive for the 4 months of the year that it gets cold (below 65 degrees). It lasted until at after 2005 when the new owners remodeled and removed the system. Solar electric was still a pipe dream in 1975, She was very pleased with the system. She figured it paid for itself in saved electricity cost in a little over 5 years. 25 years free hot water.
Wonderful video! I'm looking at building a hot water shower using a solar water heater at my off grid cabin (located on an island in the woods, in Sweden). This just convinced me even more that it's the right route to take. Though I will probably add some small PV or Piezo element to run the pump - since it only needs to circulate during daylight - when the heat is produced and than just let the hot water be in some form of isolated tank. With a Piezo one could also use the pump while the box is warmer than the outside, or double up with a water heater around the chimney from a sauna - or something like that. Great tips on cost savings and where the most money can be saved. Keep up the good work, still loving the channel. Greetings from Sweden!
There are combination solar panels available, that do both PV and thermal in one. One positive side effect of this is that the PV panel is kept relatively cool, since high temperatures degrade performance somewhat. I've no idea if there are distributors of these in Sweden - I've not found much in Norway - but there are several companies in France, Austria etc. making such panels.
@@koma-k I've not heard good things of these combination panels. What was said is that the underlying thermal panels won't get hot enough and may leak, thereby damaging the PV. Your results may vary.
Have you considered a Stirling engine? Back in the 70's there was much talk of a thermal pre-heater called The Copper Cricket. I remember it was Popular Mechanics or Popular Science magazine innovation of the year. There were big problems in balancing the system, that required factory trained technicians. I haven't seen much of it since.
@@wilfredvanvalkenburgh2874 Can't say that I have, but I know of it. Probably a bit overly complex for this application, concidering others (less technical people) will use the system frequently, I try to have it work as "domestic" as possible - and automated. As far as I can remember, a Sterling engine needs a little help starting. A PV or Piezo just delievers power to an electric motor. Quite self contained system.
This was a great video but I’m really looking forward to the air-crete videos you mentioned. In particular, I can’t wait to see your version of a foam generator and your foam formulae because I think bubble size will have a big impact on strength and longevity, and that is where other experimenters fall short. Their bubbles need to be like shaving cream instead of like dishwashing bubbles. Also, a comparison of Portland-based cements to others such as high-strength cements (aluminosilicate cements?) would be interesting. A challenge: can you cast an air-Crete “board” as strong as wood that’s low cost (minimal metal)?
Would be interesting but I think unless it's GFRC that challenge would be impossible. Concrete holds well in compression, doesn't hold well in tension, while wood holds well in both. I think in theory if you were able to create air crete with a solid outer shell, like a kit kat bar, you might be able to create something similar, but it's failure form and deformation would be very different from wood
On a similar theme - I find vacuum solar water heaters extremely facinating. The fact that you can get an almost boiling water out in the winter, when it is easily -15 C outside is amazing.
This is great. I get so many idea from your videos yet don't have the time to touch a fraction of it; I feel like I'm always playing catch-up just in terms of skills and time to get stuff done. Keep up the good work.
Hello! First of all, thank you for your amazing content. I am a big fan. Aside from that I work as an electrical engineer, building solar power plants. I am not sure if you adressed that on your video, but solar panels have an "optimum" operating point, that changes over time with solar irradiance, temperature and other factors. Normallly a controler is used between the panel and its load, either with PWM or MPPT tracking. Keep up the good work! Big hug from Brazil! 😁
I didn't cover that directly, but the optimal resistance for these particular panels under these conditions was measured and that is the resistance we used. An MPPT controller will accomplish the same thing automatically as the conditions change.
First thing: no MPPT on the solar panel? Second: if all you're interested is heating water, running an air source heat pump instead of a resistor bank off PV would have gotten you much better performance.
First: heating is by definition 100 % efficient, aka. the resistors are converting all the energy they get into heat. Second: We're making hot water here, not hot air. But, you're right. A heat pump beats everything in terms of "efficiency"
Wait! You are suggesting that solar energy receives government subsidies and fossil fuel does not! Not to mention the cost of remediating impacts on global climate change.
The end user of any system typically makes their decision based on the apparent or adjusted cost to them. Each of the costs of material production, transportation, construction, and end of life disposal has an effect whether or not those costs are all reflected in the purchase price. Each level of government and industry may have fees or taxes or other adjustments applied that change the cost to the end user. Life cycle analysis is one name for the discipline that studies all of the actual costs of the use of materials and their impacts on society, the world, etc. Solar cell production and acquisition are affected by various levels of price support, subsidy, taxation, fees, etc, just like all of the other inputs to this system including the petroleum and plastic companies that create the tubing.
You people are confused about the intention of the subsidies. You are right now currently not actually living a carbon emission free life. The free market says that you deserve to guzzle oil and it will be cheap. Living a zero carbon life is just more costly or inconvenient. State subsidies are there because it spreads out the costs evenly. That's good public policy. The negative effects of carbon emissions are collectively experienced so the costs to avoid the negative effects must be managed collectively as well.
@@rcpmac No. I don't see how my comment leads you to think this. It could be subsidies for fossil fuels, wind farms hydro dams etc. I'm simply saying that to make reasoned decisions we need all the facts and that they are frequently hidden or obfuscated by governments and other financially interested parties.
@@rasen84 The "free market" price of oil is an Illusion. I believe you understand that, but was not clear from your post. Gas and oil can be as high as $300 per gallon (combat zones), but the cost of burning oil, and the waste of plastics produced by oil, maybe the cost of our planet.
If you're interested, I can show you how to make an insanely cheap solar thermal concentrator that is >95% efficient at heating water, costs 1/8th the price of the solar water heater you built ($15 total for 1m x 1m), works in the winter, and if insanely easy to build. It uses a vacuum tube as the collector, 1mm acrylic mirror sheets as the parabolic reflectors, and a copper heat exchanger to pipe water through. Very similar to the parabolic concentrators that exist today, just made for 1/50th the cost of commercial oil fed units. The temperatures inside the vacuum tube easily reach 600-800F, even in winter, almost none of that is radiated away (because of the vacuum), so all of it goes into the water. I've built several versions myself, got lots of pictures and parts still lying around. Very simple design, just 2 sheets of acrylic, one bent into a parabola by tension, plus 2 side pieces that hold the vacuum tube in its position, assembled by hand in seconds, no tools required. Would love to show you how it works.
I've done this experiment myself: When it is really cold out and you are wanting hot water, the temperature delta is going to highly favor the PV. The efficiency of it goes up as the solar cells get colder, while the flat-plate is going to fall dramatically as the delta between outside and water temp increases. Even evacuated tubes can no longer keep up.
This is exactly what I am concerned about myself, otherwise, I would have done it also. PVs are also good to generate electric power for everything else as well.
I read an article of a home heated by water run over black aluminum roof panels. This provided hot water for the home and also heat for forced air heating. The hot water was collected in a 1600 gallon container in the basement. The water tank was surrounded by large rocks, then a layer of insulation. Air was blown through the air spaces between the rocks to heat the home. The fuel usage in Virginia dropped from about 690 barrels of heating oil to about 90. I think this was a journal article in Solar published in the 1970's.
It's pretty close with the 2 panels of glass. You could vacuum between the layers and put argon in to improve it, but it isn't going to make much difference until you are below 0.
I wouldn't think the thermal mass of the enclosed air would make much difference. Remember he covered the water panel to prevent preheating it, and it still outperformed the PV panel as the air heated up along with the tubing and inside paint and so forth. If anything the enclosed air helps equalize the temperature of the tubing from end to end. Plastic tubing doesn't like temperature differentials very much. Speaking of temperature differentials- early panels used copper tubing, likely because it was relatively chap at the time and much easier to work with than stiff plastic (and is UV proof unlike the PVC tubing used in early non-copper versions). Copper tubing also transfers heat through its wall better than almost all plastics meaning it heats the water faster than plastics. It still needs a good flat paint though as it's a fair reflector of heat.
@@jmaus2k You cant pull a vacuum on such a large flat piece of glass, it will crack very quickly. If you just want to replace the gas in it, you'd just flush it with gas instead. Probably not worth it though.
@@markfergerson2145 The vacuum in the evacuated tube collectors is there for insulation. Just like in a vacuum insulated termos flask. Thermal mass has nothing to do with it. With the air in the collector like it is now you conduct the heat trough the air to the glass, and right trough the glass to the lower temperature outside. While with a evacuated tube collector you only loose the radiative heat out to the glass, not any convective or conductive heat loss like you get with the air filled collector. An evacuated tube collector would preform a lot better than the DIY collector he made here.
I've looked at making these. I would probably put some form of insulation, maybe spray foam, to help with the cold colorado winters. I would like to see how the antifreeze would work against regular water or salt water if you rather not use antifreeze. One downside of these is the time it takes to heat the water. 15L isn't a lot compared to a standard family water heater. I would be interested how quickly water heats in an open system as opposed to the closed system you made. These are very popular in Greece. They are on nearly every roof out there.
These techniques and systems are not just at lower latitudes. Heat (and “cold”, collected during winter) storage tanks are also common in the Netherlands - using large temperature range liquids - or so I was told when I was doing (unrelated) engineering work there. I wish I would have asked directly, but my interpretation of this at the time was that the systems were probably using ethylene or propylene glycol. Superior insulation is obviously, absolutely essential. The way it was explained to me, with the system continuously being heated and with the volume being large, the efficiency and utility ends up being quite high. Naturally, energy is still harvested at some rate, be it faster or slower. But, I guess the overall point is that it can be practical, once the scale of the system is sufficiently large. Although I have no information to substantiate this, I suspect that systems using this technology are also using small demand heaters (electric or natural gas) to boost the tank temperature water up to that which would be used by, say, a bathroom shower. Edit: …along with antifreeze/tap water heat exchangers, if that wasn’t already obvious. (Maybe the demand heaters and heat exchangers can sometimes be integrated? I should look that up…)
Typical antifreeze/s offer a significant advantage for heating/cooling systems that use pumps or convection to regularly circulate water: they significantly reduce corrosion/galvanic reactions. Even though those reactions are fairly slow, they do create abrasive precipitates (for example, aluminum oxide - commonly used to make sandpaper) that can easily cavitate, and therefore destroy, structures in the system over time. I’d stay away from salt water all together, for this reason. Although I thought it would, we found that using distilled water (as opposed to municipal water) alone doesn’t help all that much.
A friend made a system long ago. It uses discarded uPVC double glazing panels and discarded domestic radiators. The boxes were also made from waste and recycled material. An small electric water pump was purchased from a scrapyard. The only things he had to buy were the pump, hosepipe, insulation materials, paint and support fittings. He is in central England, and has almost never needed to use his electric water heater, even in our coldest weather (about -10°C), for over 25 years.
I hope you get a chance to build a pop can heater. I built one at 4x8 ft. and it tripled the ambient air temp outside. I also moved the air through it with a 5 in. computer fan driven also by a solar panel (12in.x16in.x7watts). It was easy to make with simple materials. I used a 1/4in. 4x8ft. sheet of plywood for the base. I made a 4in. side using 1x4in. around the perimeter and lined it with chrome bubble wrap. The top was covered with a clear plastic normally used to help insulate windows, and a second layer placed over top of wooden bows of wood cut to 1/4x 1in. to give it a better insulating factor. The bows were slightly longer than 4ft. so they had about a 3 to 4in. lift in the centre to hold the second layer away from the first. The pop cans were easy to prefabricate by using a can opener on the tops and a hole drill to open the bottoms. I used 100% silicone to glue them together placing them in a long piece of angle iron to keep them strait till dry. As it is currently outside in the snow, I cant remember how many rows I put on each side but it was an uneven number, like 6 rows on one side and 7even on the other. Now don't be confused when I say there are two sides because what had done is built a 4x4in. plenum at each end four ft. wide at the top and the same at the bottom but it is divided in the middle but only in the bottom plenum. So now the air comes in through a 5in. hole drilled in the bottom on one side of the split plenum it then goes up through 6 rows of cans held in place by 2in. holes cut in the upper and lower plenums. Then comes out the top into the upper plenum and goes across and down the other 7 rows into the bottom plenum then out through the 5in. hole and is exhausted out the 5in. fan. In an country where it gets extremely cold in winter months, this unit will work very well as supplement heat, as long as there is sun, which I don't get through the winter months up here in Canada. Ya so it was a bit of a waist of time. Truth is I just have too many trees and not enough sun. Thanks for all you cover in so many videos, sincerely Bill Campbell. PS sorry if I misspelled anything.
@@lordjaashin yes but over the life of the product(s) it might be cheaper and also with a heatpump with a cop of 5 you get a lot more out of it. so a test of the roi with a heatpump involved aswell would be interesting
@@niklasxl the problem with heat pump is it needs to be run on grid electricity. it cannot run on PV panels unless you have huge array of panels, battery banks and MPPT controller. it might be more efficient than solar heater but what benefit is the efficiency when its high price turns away majority of customers?
@@lordjaashin it's totally fair if you want to.maxomimisr heat and have a fixed area but unlimited funds. you also need to consider what the costs really are, if you have a large installation, say a 10kw heat pump, that's a huge number of panels, the extra cost of the heatproof over 25 years isn't so much. On the other hand if cost is the limiting factor nit space for panels, consider that for say 2500 bucks you can get a different area of thermal vs. Pv panels.
Being in Australia and trying to keep the heat out of buildings, I'd be very interested in development and testing of a DIY barium sulphate based paint. Lots of recent research showing benefits, but sadly no products on the shelf yet.
DIY is the route. don't make yourself dependent on corporate vultures and wait for them to rip you off with products that you can make your self easily
And if you live in tropical environment in this project you can eliminate the insulation (glass) and leave the tubes exposed. If I had to build one, I would use two reservoirs, one on the roof and one underground, to have thermal insulation on colder days or long rainy periods.
I purchased a house in south Florida with a solar hot water system that "didn't work". A small amount of tinkering, mostly replaced thermocouples, and air purgers made it work again. I only ever turned on the electric backup in December and January. Water temp (in the tank) ran from 120 to 180 degrees. Yes, I installed a thermal mixing valve. Most of the people who removed those systems didn't want to be bothered with maintaining them.
If you're putting the solar thermal system onto your roof, remember to account for the extra weight involved. You might need to reinforce the roof rafters.
True, but don't forget most of the water will be in an insulated storage thank that's not on the roof. A 100 feet of 1 inch ID tubing would only hold a bit less than 4 gallons on water so you are only looking at about 35 pounds of water.
They suck. Solar hot water was very common in the US before natural gas and oil and to a lesser extent bottled propane were cheap and available. They don't really work very well unless you live in the deep south and have lots of sun available most of the year. A lot of the efficiency of the system is lost because of anti-freeze. Direct heating is just a lot more efficient than adding a heat exchanger. They just aren't very good at transferring low grade heat (when there is not a very large temperature differential between the antifreeze and the water you are heating.)
That's pretty silly. I have 13 12ft by 4ft solar panels to heat my pool. They don't weigh much full. If you are scared of your roof, the thing to worry about is how much things contract and expand. Even a rubber boot will wear a hole in shingles in under a month. A bit of flashing under contact surfaces solves that.
@@tarstarkusz your generalizations are misleading. I have a well designed solar water heating system which uses a heat exchanger and propylene glycol antifreeze and water mixture, in Ontario, Canada that continues to work well 14 years after installation. On the other hand, I'm pretty sure that there are poorly designed products out there that do suck but that doesn't mean the technology itself is the problem!
13 seconds in and I just punched the air and yelled "YES!!". I'm glad this topic will be explored in the level of detail and care you put into your projects.
I was searching for "e-glass" but found it to be the high electrical resistivity fiber type glass for electrical insulation. Then I learned something: The reflective-coated thing is called "low-e glass" and there are two very different types of it: - "Passive Low-E Coating" is an Indium Tin Oxide layer designed to gather as much heat from the sun without letting the heat out - "Solar Control Low-E Coating" is a thin silver layer designed to improve thermal insulation both ways, it is used in hot climates where it doesn't let too much heat inside. The former is obviously the best for this project, while the latter might even be counterproductive. This is quite an interesting topic, it would be interesting to see how it performs when it's cold outside or when the water gets really hot. How much does power vary over temperature (difference), at which point is it the same as the PV panel. As for the PV, its efficiency is much more consistent with a constant voltage than a constant resistance load. Around 75% of the OCV. Anyways, great video, these things always get me curious!
I have a 9.6 Kw peak grid tied pv system to replace some of my electrical load and a solar water heating system to replace some of the propane gas fuel cost. Both systems do not replace all of my energy loads, but, they definitely do help. I am located 30 degrees north of the equator in north America and we get a LOT of sun most of the year. Might as well use it, as it would otherwise just heat the roof of the house. The solar water system is 25 years old now and I have had to service the panel on the roof once and just replaced the pumps in the heat exchanger this year. Set for another 25 years, I guess. Thanks for all that you do and introduce our younger generation to the application of science.
It would be interesting to see an experiment where you want to see how much stored Kilowatt you can achieve, between the two sources you have, which is PV panels verses solar water heating which is converted to electrical energy. What I notice in your experiment, is that the solar modules needed to be placed correctly as to the azimuth angle to the sun to optimize the efficiency of the pv array. I have both systems at my home, where I am totally independent from the grid for both electricity and water heating. Each on their own are excellent in their own application. Your experiment was very interesting, and makes one think. Thanks.
Hey Nicolaas, i see what u mean, but, wouldn't putting the solar water heater also to the correct angle to the sun make it more efficient thus giving the same results as the video? IDk it's just a possible asumption, although maybe due to the way a PV panel its built the angle affects it more than i think idk or event maybe once the water heater stars to reach a certain temperature it just reaches a limit where's maybe the PV panels start to have advantage. (Also the water heater is slightlly bigger in the video but i think he said he had it into account) Sorry for my english im spanish.
Since you mentioned aerated comcrete (aircrete), do check out aircrete with shredded styrofoam, for budget insulation. The video "Aircrete on Steroids, Aircrete Styrofoam. Build Cheap" by "Stephen Williams" says that adding shreded styrofoam to aircrete makes it 80% as thermally insulative as normal styrofoam of the same dimensions. Also, I wonder if using cooking oil instead of water would make the solar water heater just as easy to pump and not much worse in used thermal capacity. For example, some motor oils freeze at -20 F or -28 C, though they might be too thick for a solar heater, but it might be useful to consider some other thermal liquids, even if their price is higher. Or maybe adding metal powders, like you did to the thermal paste, would help by increasing the thermal capacity of the liquid after the antifreeze lowered it. At that point, the problem would be to make sure the pump isn't damaged by the thermal liquid, but taking all those things into account might help find some other more-efficient strategies. Another thing to take into account could be using stainless metal sheets to reflect more sunlight onto both the solar panels and the solar heaters. "Sergiy Yurko" has a video called "Very cheap ( $15-40 ) solar collector-concentrator that does not need a tracker", in which he shows how specifically to make steam having snow on the ground, using concentrated solar, and while solar panels need to not have their temperature too high to work properly, they also stand a lot to gain by concentrating sunlight onto them in the colder seasons, while the solar collector-concentrators only need a different thermal liquid to increase their working temperatures significantly, and motor oil might work wonders in that case. Sergiy Yurko has calculated the price for the heat of concentrated solar to be about 0.5 cents / kWh in the latest video, and other similarly small prices for other setups, in his location.
Aircrete Styrofoam - Stephen Williams is a new up and comer aircrete channel that he shows measurements / results, unfortunately harry has not been posting that often as of late. Sergiy Yurko - such an underrated channel Wish Tech Ingredients will also look into Rock Stove and Rocket Mass Heater. Ive seen a lot of designs but I think Matts is the best th-cam.com/channels/XnaWrIqSe7BgrlD14zUFAw.html he is very helpfull and friendly.
Its quiet a unfair comparison. With a Solarpanel you get more exergie, which can be used to power a heatpump instead of an resistor. This would give you more heatenergie when the heatpump works with an Coefficient of performance of 3. I dont say this would be cheaper. If the solararea is limited this would maximize the heatoutput to win your test.
I don't think it's fair to use a heat pump's thermal coefficient as justification for the inefficiency of the PVs. Following that logic you could plug a light bulb into the PVs and say they're infinitely more efficient at producing light than the direct heaters, which would be true but completely meaningless. The point of the video, as I understood it, was to compare the solar energy collection efficiency of the PVs with the direct heater panel, not to compare how the energy is used, which is why resistive heaters with their near perfect energy to heat conversion are ideal.
@schutz nhil Turning electrical energy to heat energy is the most efficient thing he could do here. Claiming higher efficiency with a heat pump is not accurate at all- assuming a motor drives the heat pump (~60% efficiency), you still have to transfer that thermal energy from the air to the water (using more motors at ~60% efficiency.)
@@LeObsidianCraft 100% is nearly a low bound when trying to convert electricity into heat. For sufficent small tempratur differential of course, like we have in the test.
The nice thing about solar water heating is it can be economically scaled to the size you need. Our farm had a tin shed the size of an out-ous with a black 55-gallon barrel on top to heat water for a shower when coming in from the field. Being 60 miles west-north-west of Wichita Falls, Texas a black barrel was good enough for most days in April through October. It was built before 1947. I helped a neighbor near Frisco, Texas heat his pool in 1972 by laying a 3/4'" black plastic pipe on his roof and running the pump with a switch on a solar cell that turned on in the afternoons with enough sun. The pipe drained back into the pool when the pump turned off, I think it cost $60 or $70 bucks. It was still in place a couple of years ago.
Another great video! I'm sure you've thought about this, but it would be interesting to do a DIY Sterling engine build (or something similar) to see how efficient electricity production could be from the heating panel. It certainly won't match the PV panel efficiency, but could be worth considering once you take into account all the factors
It might! We can't really know without actually getting the Sterling engines or other thermoelectric generators into place and testing them in real-world situations as in the video above.
With an eye towards maximizing the use of a rooftop, how much heat can be extracted by water-cooling the photovoltaic panels from below? My understanding is that the PV panels are more efficient when operating at a cooler temperature?
To start it would work as good as both of the system but as the water under the pv panels heats up the panel loses efficiency due to it warmimg up past whatever temp it would have been with ambient passive cooling
First of all, thank you for your excellent explanation and good images of the technique. I myself have a finnish house , sawn and custom from Finland . I live in the middle of our country . construction was completed in 1980. At that time, we were already aware of the necessity of being finite, ie becoming more expensive for energy, from the ground up. I used much more insulation than was supplied and also prescribed. Later I bought a used water tanning heater. of 7 m2. with a storage tank of 250 liters , also a still working one . Heat pump for shower and drinking water heating. Inh 300 liters . Shortly in 2013 16 PV panels, Mono Crist, 4400 kW per year. and shortly a heat pump air water air . for my hot air heater. I used for this house of 13x14x9 meters high and a basement of that size area. around 1200 M3 gas. and 4400 kW of power. per year . Now I'm testing my house without gas. I did the test for my Hot air heater with a New WP Boiler (175 liters) which is now available as delivery. of shower water running with it. it turned out that my 35 KW radiator that I bought to do the test . With my Midea heat pump I can heat the house with an average of 400 W. energy from the PV panels. A whole story. but without being able to heat gas in this horrible time with that Putin war . Makes me feel good . Read the book " the black gold " 25 years ago . confirmed that I was right to make all these savings. I am now 75 years old . and healthy to do everything an older man can do in his life . thank you again for your excellent contribution to all the problems we face . Sincerely, Giel Klaver Hulsterstraat 2 4116 EZ Buren ( Gld ) The Netherlands .
Thank you for this video. Our combined knowledge comes from our combined experience, and your experiments add to the pool. It would be nice to see the final numbers, specifically time and temperature gain. It's hard to conduct such experiments without any bias, for example: the hot water panel is insulated, and thus prevents heat loss from the water that circulates inside it. On the other hand, the pipes leading to and from that panel are not insulated, so there's unmeasured energy loss there... hopefully all the small biases cancel each other :) I wonder what we'd find out if there was another panel which combined both approaches, i.e.- heating water with the excess heat from PV panels, which uses more of the light's spectrum, and at the same time cools the panels, which increases their efficiency, would the extra work and cost be worth it in comparison with the simple water heating panel?!? Also, I think such experiments need to account for the intended use of the system, since converting one form of energy into another, (electricity to heat, and vice versa), involves some energy loss, plus an added cost/complexity to the system itself, and to its maintenance. Regardless, your experiment seems to show that the gain in energy harvesting efficiency is far greater than the loss during energy conversion. Thanks again.
I live in germany, and like many here i have solar water panels on my roof, in my case 20m² of Flat panels ive installed myself. You got a bonus from the gov for changing your heating system to condensing combustion + solar system at the time when i did this. My oil consumption significantly dropped because of these changes. I have 1m³ water Tank I heat up using solar & oil (which is only fired when the top section of the tank falls below 50°C). Later i installed a water jacketed wood oven in my living room, which allows me to heat my house with solar and wood from around late february to december, only in deepest winter i use the oil to compensate. Would i do it again? well, maybe not so much... The heating system is very complex and with that big solar array on the roof, in summer i have gobs of heat, i have to dispose of, otherwise the system ends up overheating and breaking. My godfather has had a solar system with photovoltaik panels installed in 1991, which is still running at around 75% its new peak power 30 years later... and he had very little problems with it so far. Using modern panels together with a heat pump you get similar heat output as the thermal system and have the advantage of gobs of elektricity in summer which you could use to run an AC, maybe charge an EV... Even home batteries are getting cheaper so you can store it. And: On a cloudy day, my thermal panels arent collecting at all, while a good photovoltaik cell is still collecting 15-20% its peak power...
@@jaejohnson4631 Yes but you have to take into account the very harsh environment on a 50° direkt south facing roof. Covering it by hand is challenging/ dangerous, could only be done seasonally + most materials dont live very long due to intense heat& UV. Far easier to just keep it running and dump the excess heat.
@@tiboreeb5360 the time would be early morning before sunrise, after it has cooled overnight. Of course covering a hot anything is not a good idea, although I have seen people make adjustable shade systems. Also it must be covered in white, no other color, which can be conspicuous.
@@jaejohnson4631 you dont understand... that roof sits 7Meters above ground and has a steep slope. you wont do anything safely without a scafolding. And the problem with the material isnt that the roof itself is hot, its that whatever you put on that roof will endure extreme temperatures and UV during daytime. The tiles reach far above 100°C, and even a white surface will get scorching hot. When i was installing the system, i had to wait for cloudy days, because when the sun came out, you litterally had only a few minutes until you cant touch stuff with your bare hands without getting burned. And yes, you can build motorised shadings etc.. but as far as i have heard, its expensive and very high maintenance.
@@tiboreeb5360 I see. How are you disposing of the excess heat? My suggestion may not be useful in your case, but I hope others reading this thread for ideas as I did might find our suggestions/warnings useful.
Great job! We are at Capricorn tropical line. A few decades ago (1970's energy crises), my dad decided to build a solar water heater. It was a interesting introduction to energy balance and engineering for me, at high school at the time. The colector had 2 by 4meters, it could suply with very hot water, 85oC, enough for the needs of a 6 person house. We had to be carefull with hot water burns.
Counting disposal as part of the overall cost!! This is one of the reasons I really enjoy the videos on this channel. Plus twenty years from now one of these two systems will be running the same as ever. Also looking forward to the aircrete episode. Hopefully EPS beads/chunks in the mix will be considered?
Please note that this is highly dependent on which panels you get and their warranty. Tier 1 panels are warrantied to still produce 93+% of their rated power at 25 years. After that, they fall off 0.30% a year. If you're running a single solar panel, this might be an issue. If you're running a 5kW system, not so much. Basically at 35-36 years, you'll have just hit 90% efficiency. Note that, depending on your location in the world, your system may actually over-produce by a few percent as well. Which could take some of the bite out of the performance degradation. You could also opt, early on, to simply tack in a few extra panels and/or storage. You may also find out that your consumption actually goes down over time as more energy efficient appliances enter your home.
Not sure if the heat collector will make it 20 years, especially not with strong sun and weak maintenance and frosty winters, but yes it’s better long term stable than the PE panels
Interestingly in Japan, disposal is included in the cost of many devices, such as computers, and they come with a sticker you need to have on the device when you hand it in for recycling. (I have never actually used this since I usually sell my devices while they still have some value left).
I think it's because it's not flashy like other engineering channels, and the videos are long format. Sucks, because it's so dedicated, humble and thorough, it gets less views and subs
Thanks for sharing, Always find your videos interesting and well made. From a solar hot water sight a few years ago that sold the vacuum insulated glass tube water heaters. They were located in Binghamton NY and said the infrared sun light makes it thru the overcast winter sky and makes hot water year round. Always thought it might be interesting to see if a solar hot water driven sterling motor powered generator might stand up to a photovoltaic in the winter. But secretly I figure if anyone can build a residential sized thorium LFTR it’s you guys.
@@mangeload they only have water in the pipes and collector headers, typically they use a glycol mix with a heat transfer at the water storage tank, I believe the glycol not only prevents freezing but increases heat transmission. They also have a gravity drain back tank with the pump driven by a solar panel, if there is enough daylight to run the pump it’s assumed the heating panels are also ready to go.
@@tbix1963 Thank you for your response. I have an idea (im sure im not the first to think of it) to run a low watt (3W/foot) 12VDC thermal pipe trace on a thermostat that controls when the trace is actively heating, which is also thermostatically activated so it will only heat where / when needed. The purpose of this setup is to prevent pipe freezes while minimizing power consumption in an off grid system. This will be efficiently accomplished by avoiding an inverter's idle draw, and maximized by running low consumption DC pipe trace & bypassing inverters altogether. This should be a practical and inexpensive way to prevent pipe freezes (much cheaper than new plumbing) & will provide a small backup supply in case of emergency power outage, that can be easily built upon. And I'm doing it all for between $500-$600. Here is my planned setup: 100 amp hour deep cycle battery, 40amp MPPT charge controller, 100w mono panel, cables & wiring, connectors & fuses, 400w inverter, 6 - 8 feet 12VDC thermal pipe trace (@ 3w/foot 18w-24w), thermostat, pipe insulation, & maybe a battery bank status monitor. Future plans also include 600w total solar panels combined & 4 x 100ah deep cycle batteries, & a 1500w pure sine inverter. What do you think? Any advice or suggestions will be appreciated.
@@mangeload maybe I misunderstood your problem, you have a water source that your afraid will freeze? If you have plenty of water that is pressurized a cheap solution would be a freeze miser water valve. Under freezing conditions it allows a small flow of water keeping the pipe above freezing temp for the price of some water. Freeze Miser, can be found on Amazon for about $30. I’ve seen it used by ranchers in subzero temperatures to water cattle from garden hoses lying on the ground. As for your electrical solar solution, I’m no expert but it sounds like your possibly going in the right direction. I’ve used heat tape before to winterize pipes in a drafty cellar before but always found them a bit unreliable, compared to letting the water trickle. Good luck with your project.
My wifes dad a well driller 50+ years ago designed a rooftop Cooper tubing box that heated up by the Florida sun. It used no electricity only gravity flow. Guess he was way ahead of his time. It worked great too, and STILL WILL
I would expect to be the heat-only collector to be at least 5x as efficient as the electricity to heat one - assuming a 12-15% efficiency in the pv panels. But electricity is so much more versatile than heat...
5x is a bit high for a ratio between PV and Thermal collection. If the PV panels are 17-20% efficient then to by 5x the thermal collector would need to be at least 85% efficient... Which is asking too much from any conversion device, let alone a home brew water heater. 3x would be more like it... Also, inadequately addressed is this: as the thermal panel warms it re-emits and, low-e coating or no, it has a nice big eye looking up at the cool sky for radiative exchange (aka thermal loss.) Hotter collection means hotter emitter and lower net efficiency. It is still higher than the PV but not 5X. This demonstration is a good start but, as you mention, the versitility of electricity (it can be converted to light, computing, entertainment, heat and even money) means it can tolerate a less efficeint conversion process because its product is more economically valuable. But like the host said, if you have a thermal load you know you are going to serve.... thermal collection is a great way to go.
@@gamingSlasher The idea of reducing it to one common measure (Temperature rise) is good as far as it goes. Isolating to understand is a great practice. But they fail to do the other contextuaizing work to help viewers get the big picture. (inpart creating the chaotic mess that is the comments stream below.) They are trying to make the argument that we should serve heat loads with heat collectors (for efficiency) and us electric collectors for electric loads. There is a bit of free market rah rah thrown in. ( I think it is more complicated than just some customers paying for others to enjoy solar, but this is kind of extra off hand contextualization which is where we all get caught out extrapolating beyond things we have deeply thought about.
You covered a bit the topic of harvesting radiated energy. In the previous videos you covered the topic of the cooling by liquid evaporation process. What about the cooling process by emmiting far IR radiation into the sky? You mentioned the film that alows the visible light to come through the film but doesn't release the IR outside. Is there a film that releases far IR instead of light/near IR?
Would you consider the efficiency of the LPG system? I know it works decently, and you know this as well. I think lots of people from the audience would benefit from such knowledge. They would listen if it could come from you guys.
I originally determined to skip to watch just near the end. But turned out I keep scrolling back to a bit earlier that where I started again and again as you keep giving some very interesting info that I have to scroll back to see where it come from Dang what a channel
Here's a project idea for ya... use solar hot water to boil something like pentane or something with a similar boiling point in a closed loop system in order to create a pressure that can either turn a small low pressure turbine or even a piston of sorts to generate electricity. Pentane looks like it should produce around 75psi at 100c which could drive a small turbine, or maybe better yet use low speed opposing pneumatic pistons to turn a shaft. Larger pistons can create a lot of force even at lower pressures as long as you can create enough volume and not allow the temperature to drop much until the vapor leaves the pistons. Worth a shot! And to anyone who doesn't think 75 psi is enough to do anything (compared to say high pressure steam turbines) take a 6 inch piston for example... at 75 psi it has a force of about 2120 lbs.
This wouldn't give you much. In the best-case scenario, you will get Carno cycle efficiency ((t hot) - t(cold)) / (t cold). It will be about 20-30%. So you will go below the efficiency of the PV panel.
@@fabriglas Is right. Use a Sterling engine to take advantage of the high temperature gradient between the water storage tank and ambient air. You'd insulate the entire storage tank except for the one spot the Sterling engine makes contact with the surface.
All that matters is the amount of sunlight, which is proportional to the area. A lens would only help if that lens is bigger than the solar collector and then concentrates the light onto the collector--in which case you could simply make the collector bigger at probably lower cost.
I have a four foot square fresnel lens and although it concentrates intense heat in a very small area, it does nothing to the area outside the focal point. Also it is very directional and has to track the sun or it doesn’t work. You can melt lead or even concrete with it but it’s not practical for many other purposes.
I would be curious to know the absorbance of the solar collector, as in what percent of the solar energy is actually absorbed, and how much is reflected from the paint, or absorbed by the glass.
Based on solar panel would be near to 20% efficient and the solar heater increased the temperatur about dobbel, the total should be around 40% efficiency.
Best commercial PV extracts about 23% of available insolation. Best commercial solar water heaters get more like 75%. If you heat your water with electricity it usually makes sense to install solar water heating before going for the PV, but check out the costing before you do.
Using both systems would be preferable. I’ve seen a lot of houses with sun heated water, but they are always disassembled because no one wants to maintain them.
Maybe you might like to explore solar ovens with different material incl aircrete as content especially in New England to show the power of gamma radiation being converted into thermal! You can put solar concetrating fold out wings on it too. Very interesting subject and so many great ideas i have seen! 👍🏻
I haven't heard of any efficient way to do that at small temperature differences. There are places that use lots of mirrors over large areas to drive generators:
@@AmbachtAle The Carnot efficiency limit for a ∆T and max temp of 100°C (373 K) is about 26%, so a really well designed Stirling engine driven by this could be competitive with photovoltaic panels. Or at least be in the same order of magnitude.
@TechIngredients I just bought a small house in a remote area in central Texas that has high electricity cost. We even have high LP gas cost because we are remote. My current water heater is old and expensive to heat water. I'm going to supplement my hot water with this type of capture system. This could even supplement a small sub-floor heat system for my bathroom too. Thank you for your great instruction and solid inspiration.
To everyone saying “why not use a heat pump water heater”. Yes, a COP of 3+ is typical. However, these pull heat from your house and it becomes a rather convoluted comparison. If the house has a net heat load (hot/summer) then this is extremely efficient and takes load off the AC. If the house has a net heat loss (cold/winter) then you now need the heat from your primary heat source. If that is gas/resistance/heat pump, we’ll you’ve just moved the actual heat source to that system. I think this is an entirely fair test. As someone in commercial HVAC, I rarely see heat pump water heaters. Electric resistance heat, I see all the time. It’s definitely the predominant electric water heating technology used.
This. I think heat pump water heaters are great for people who have the $2000 to spend and never mind the tank has the same warranty as the $650 gas-fired unit. Problem is I live in Michigan where electricity is 14 cents per kW-hr and nat.gas is 87 cents per therm. Now what I love is technology designed for DIY and longevity. You find me someone who grafts a heat pump onto one of those fantastic old monel or copper-tank water heaters from the 1940s (never rust!) and you'll have my attention. Friend of the family has a cabin up north with a Lochinvar water heater from 1957. Works great. Blows my mind.
Something I've always wanted to do is add Peltier plates to the backs of PV cells, since they'd be in the sun all the time, and the cold side just leave ambient. What do you think?
You could buy electricity until the end of time before you make a profit on pelter elements, probably the most inefficient way to cool or heat, but to create power... You're better off pedaling a generator
Another fantastic video, first thanks for the intricate detail. In regards to cost and societal cost and subsidies, you should nor forget to mention that keeping greenhouse gases down is in fact more important than any short term inconveniences from subsidies. Of course that total life cycle (environmental) cost is the important one.
Me: *Building PV-system at home* Tech Ingredients: "Should you really use solar panels?" Me: "Oh, that's interesting, let's see!" TI: *solar heater* Me: *lives in Finland* You do that then.
What is the surface-temperature of your panels? You may be able to squeeze a few extra % if you force-cool it. The warmed coolant is a bonus. Adding antifreeze will be a pain though :( What do winter temperatures look line in FI? -40'C ?
You can make a heat exchanger on the inside of your house like he said in the video, and run antifreeze + water in the main system. Even in subzero Temps it will still heat your water a little bit, enough for your main heater to use less fuel.
@@lordjaashin For serious production yes. Most of my power comes from a couple 300w wind turbines, but solar panels are quite useful for about 6/12 months of the year.
@@AdityaMehendale -40C is a rare occasion. It's something that your home should be able to sustain once or twice a winter. -20 to -35 in norther Finland is the usual business.
Thank you for sharing your insights to this project like the metallic glass and the camouflage spray paint you used. I really enjoy your technical presentations in all your videos. I am toying with the idea of building a greenhouse and using passive solar heating either with water or circulating heated air into the ground to extend the growing season. There are many videos on youtube about passive solar heating, but I have yet to see anyone speak on the technical details such as the rate of change in temperature of the thermal storage, be it for water or soil. I know this is dependent on a number of factors (you mentioned insulation or the ambient outside temperature). In the case of heated ground, depth and the type of soil. clay versus sand versus rock will have different characteristics in thermal storage. It's great that people are posting videos of their builds, but they never mention the technical details such as volume of thermal medium required to keep an n' x m' sized structure warm. I would be very interested in knowing what you would come up with as a solution and your technical analysis.
Mhm "if the system doesn't make sense without subsidies..." but if one considers the ecological cost of burning coal and natural gas, which has been displaced onto the future generations to deal with? Who pays for it now? If it's politically impossible to introduce a kind of tax/insurance/fund which will cover it, maybe solar subsidies are the next best thing. How hot does the PV panel get? Is it possible to harvest the heat from underneath it for water heating? Would it provide some cooling for the panel, raising its efficiency? Obviously you can't get the circulating water particularly warm, or it wouldn't be cooling, but maybe if you have a sufficient resevoir of water to where it won't get very warm, you have still harvested the energy and you can then electrically heat it up a little more on demand.
"if the system doesn't make sense without subsidies..." isn't the US already subsidizing power production? Federally, to the tune of ~$15B a year to oil and gas.
Well prepared and presented. I currently have a 1800 watt PV system sublimated by a 1000 watt wind turbine. My summer home is located in northern Arizona. The elevation is 7500 feet the home/cabin is 1400 square feet I use 4 rolles surrett lead acid 6 volt batteries 450 amp hours each wired in series’s for a 24 volt DC power supply. I take the 24 volt power and I use a 4000 watt power inverter to provide 120 volt AC power
I saw one video where someone compared PV to pumped water. The result seemed to be that the pumped system worked better at lower temperatures (like up to 40 degrees), but when the water got hot (or didn't get very hot) the PV would continue heating the water until the tank clicked off. The pumped water kept losing heat in the collector and pipes and never did get the water up to "hot water tank" temperature, 55 to 60 degrees. In addition, a few hundred bucks for a couple of big solar panels (350 watts each, these days?) and wiring it up is incomparably easier than piles of plumbing to a "pre-heater" tank that feeds the "real" hot water tank. I did that in 1979 back when there pretty much was no solar PV. Not again! You have extra pipes and an extra tank to leak and replace, freezing issues and a pump (needs electricity anyway, albeit little power) to wear out and fail. There are "Dernord" electric water tank elements for various voltages and powers. I got a 1200W, 36V one for a 15 liter tank under the kitchen sink on my 36V DC system, but to avoid overpowering the solar on cloudy days, I wired 2 of the 3 "U" loops it had in series for 200W. (It did reheat pretty slowly.) I would use hot water collection for cooler water like heating a swimming pool.
I installed about 350 solar water heating systems in Wisconsin between 1978 and 1983. They were either anti-freeze or drain-back systems. Some large arrays of 50 or more, but mostly 3 panel systems with a total area of 63 square feet. The boxes were aluminum, with about 1" of fiberglass insulation. Absorbers were nickle plated copper, and laid out in a reverse return pattern. The absorbers were anodized with a "selective surface", as developed by Everett Barber and had such low emissivity that a single pane of low-iron tempered and non-reflective glass was used. In full sun when the systems was running the glass was cool to the touch. At the time, we calulated that it would take 5x the area, and 7x the cost to duplicate the energy produced by the solar thermal system.
Great video and effort. Having a thermal water panel still installed and working for 21 years without problems -just replacing the outside pipes isolation-, nowadays, I would choose a PV. Why? In summer, we have lots of hot water that we don't use, just 2 hours with sun are enough to heat the 250 l tank, and we are "loosing" all the other sun hours by harvesting anything at all. But, we still need to use electrical power for the recirculation pump to avoid overheating of the solar panel and pipes. Instead, when heating water using a PV + heat pump you can increase the performance x3 or x4, (better that the test you did that was about x2 better performance on thermal vs PV) and once the water is hot the PV panels can be used for other appliances (oven, PC, TV, air conditioning,...) or sold to the grid. PV vs Thermal panels drawback: higher initial investment (inverter, heat pump,...) PVT (Hybrid PV + Thermal panels): at least they can use the built-in PV to power the recirculation pump and at the same time to cool the PV for better performance. But I still would invest in a PV+Heat pump system.
Excellent video, thorough methodology and really helpful. I had no idea one could make one's own solar water heater panel so cheaply! Thank you very much.
I lived in Lubbock, Texas for nearly 10 years back in the early 2000's. My neighbor was a retired Texas Tech physics professor who had built a thermal battery in his garage. At first when I heard of a thermal battery I laughed. What for and why?! George, my neighbor, was more than happy to explain. He proceeded to explain that his ~600' of 3/8" black UV resistant tubing in a long box frame (~12' by 6') produced boiling hot water in a few hours each day. He had a 300 gallon stainless steel insulated container on a legs with a few different pumps and lines going out. One went to his jacuzzi, another to his hot water heater (or preheater), and another to a garage heater. During the summer, he hardly ever turned it on, but from late October until March we'd see billows of steam rising from his back yard when he took off the jacuzzi lid. It could be 40 degrees outside and you could hear the stainless steel container bubbling with what I assumed was boiling water. I know you could feel the heat when you stood next to it. George taught me a lot about physics over the years. He passed in March. Thank you ol' buddy for all the knowledge.
Awesome
Rest in peace Georges, what a wonderful neighbour he was.
RIP George
He sounded like a good guy, with a big heart and brain
From Lubbock long ago! nice seeing comments from folks out there still!
George sounds like an awesome person!
I live in Bangalore, India, which apparently has the highest number of solar (thermal) hot water rooftop installations in the world! I'm pretty sure we've had one (or two) in every home I've lived in, atleast for the last 2 decades. One of those things that you use every day, but never notice. I can't remember a day when we didn't have hot water!! There were days without water, at all, but we always had hot water 😂😂
in Syria, every house or apartment has thermal solar panels. They are amazing and work very reliable. And no, we don't use pumps, if the house is not very high. Close to the panels we have an isolated tank, which get filled by the water pressure of the grid. Then the water gets heated and the gravity does the job delivering it to your house. And yes, even in the winter when the sun comes out, we get good warm water. It is the best investment a house owner should do.
Who makes the solar thermal panels that are used? Manufacturer.
I would guess that in Syria that works for a longer part of the year than further north
@@thirtythree160 YOU manufacture the thermal panel(s).
Not hard, a couple trips to a home Depot.
"They are amazing and work very reliable"
are they bomb resistant too?
Is it nice to be able to isolate yourself so well from the civil war there?
@@thomasneal9291 Take that elsewhere, this isn't the place.
I really wish I had a teacher like you at any point of my education. You're so articulate down to point of complete understanding. It's beautiful... thank you for the videos.
I want to like your comment but I don’t want to ruin the number.
… the Beaty is, that your education is still incomplete and through the power of the Internet he is your teacher! You just learned by watching the video!
I discovered your channel a few weeks ago and I will be honest. You rekindled my love for science. I have not seen anyone explain things the way you do. Thank you for doing what you do.
Thanks!
Glad to have you on board.
@@TechIngredients Agreed. You have an excellent and thorough approach.
Questions on this project:
I know radiant floor systems recomends PEX AL PEX to stop oxygen ingress and therefore corrosion building up in the system. Can you comment on that and lifespan of this system?
@@TechIngredients One other question: Could you explain why setting the coil into a block of black pigmented concrete would be inferior? It seems that it would be a lot more resilient than glass and provide better protection for the PEX; especially from long term UV damage.
It's possible to enclose the back of the PV panel and run water through the back of it as a cooling jacket. This means you heat water, generate electricity and keep the panel cool which boosts its efficiency.
Would be great to see you attempt something like that.
Yes, this please!
This is true, PV's would greatly benefit from cooling and can double-dip on the efficiency
Correct. Semiconductor devices are more efficient at cooler temperatures- from lasers to transistors.
cool the PV, while preheating the water for the solar water system...
Also think this would be an interesting experiment though i think it would have already been a product if cost, efficiency and reliability were reasonable.
This channel keeps my faith in humanity
When I was in high school, we had two vakuum tube water heating panels on our roof in Germany. This was a great investment as is, but it became especially clear in a year when both my parents were unemployed and we could not afford fuel for the heating system. These two panels allowed a familiy of five to take luke warm showers throughout the Winter.
Lukewarm is still better than freezing, especially in the dead of winter.
This is why I like the idea of using PV panels with a heating element. You get full temperature.
@@eyeballengineering7007 only if you've got enough of them though! You'd need several times the area of the thermal system - double the area at least, just to reach lukewarm.
A more efficient method would be to use a combination of the two, with the PV array powering a heat pump, to concentrate the sparse energy from the thermal system down into a smaller volume of hotter water.
@@eyeballengineering7007
Note that this was 20 years ago. The system was quite complex with heat storage tank, and excess heat radiator, multiple electronic valves, etc.
Also the people who installed it did not make sure that the metals of the different lines are compatible with eachother, which lead to an expensive renovation, but that is just bad craftsmanship.
Today it would probably be easier to use PV panels and a heat pump. You probably still need the heat storage, because battery storage for heating is still expensive.
@@eyeballengineering7007 In the dead of winter with low sun, there isn't much power from pv panels.
I try playing these videos in the background while I'm doing other things, but your explanations are so thorough and technical that it becomes nearly impossible to follow without giving it my full attention. The cognitive nutritional density of your videos is second to none on this platform.
"Cognitive nutritional density". Wow.
@@eddietee6305 Yeah...I like that; a more interesting way of saying "information density", which is among the highest on TH-cam. 😎
@@Vito_Tuxedo verbosity!
Exactly...
Solar is the way to go!
"while I was jawboning. . . . ."
I love everything about this channel.
Except I know what boning is. So jaw boning would be like that? ....
Or is that why you love the channel...
I've seen the use of electric water heaters as overload devices for DIY water turbines in off grid situations. Which is a cool way to store or use what would otherwise be wasted.
makes sense
Also in wind turbine it's common to have dump resistor that slows down the turbine if there is no other load (batteries are fully charged or something). And the dumo resistor can be water heater.
Seems like if you finish heating the water then put excess energy into pumping water up to a higher elevation. Then it can be a circular system, you won’t have to pump as much water to keep pressure in times of peak/excess energy so it would be a great time to take a hot shower! Just like with rainwater harvesting but with electricity.
That's actually quite ingenious!
Energy storage to a heat sump is an excellent way to store energy you don't have an immediate use for. Still your first choice should be an intelligent / programable electrical load management system. It requires rethinking the way most of us use energy in our homes. A well thought out system can minimize the maximum production capacity of your system and save you a lot of up front money. Which is what I've always thought was the most attractive reasons for an electric vehicle. Make your own transportation energy and get off the gasoline price roller coaster.
As an EE, I really enjoy your work and that of Ben at Applied Science for my continuing education. No One of us knows it all but we can all press on and continue to learn. THANK YOU for your contributions in science and your empirical research which you share with all of us !!
Thank you.
@@TechIngredients
I have an idea ..
Will need a bit of thinking ..
You can use a pinned comment..
As there are 2.4k comments.. it's a lot to wade through..
It could be used for comments to improve or modify what your video is about...
I don't remember seeing... Have you done a video about using those ceramic resistors? and how to calculate the Actual resistance? What I would really like to know is a way of doing a cost effective and affordable electronic PV dump load circuit.. maybe in incremental stages and making the water heater element, from resistors and resistance wire.. apparently some say use mains voltage ones but I'm not sure..
... Back to feedback idea.. and do follow up video thanking and explaining them .. a winter task..?
I'm been living off grid over 33 years .. Low budget, no subsidies etc.. I've still got the decades old little glass panels.. I'm in the process of setting up a TH-cam channel.. this has made me think I should film and talk about the early days of those panels... they were expensive but were worth it to not hear the engine or generator running.. I live on a Boat .. monetary or environment were in mind.. my sanity and to hear the birds not coughing was uppermost..
Thank you for your channel and in part making me realise I should do a channel..
Maybe you can inspire others to do a channel of what they have done.. the more this is normalised the quicker the reduction in planetary damage...
I liked you saying about subsidies etc..
UK gov keeps giving £b to rich people here.. that makes them £s and they don't pay it back.....
You made me laugh about cursing the universe...
Sorry bit long comment.. hope of use...
Kindest regards
Mark and Bella...
What is News most people in the know already aware of that But they also know that to much hot water can be a major embarrassment where as surplus electrons can be shed to the grid or otherwise dumped
@Tech ingredients is it possible to use this hot water to generate electricity with a stirling engine?? I wonder what efficiency gains it might have over PV. Also, Stirling with solar heating is definitely cheaper than PV.
@@gauravsarraf So you are touching on the holy grail of energy harvesting. Thermal Energy (say Joule or BTU) is more useful when it's at a higher temperature. Recovering energy from low temperature heat sources (like 20 or 30 deg C) is generally not economical. If it was, oh boy! Sterling engines, Organic Rankine cycle, thermoelectric devices all work at fairly high temperatures (relative to 30 deg C). I'd love to see the creative ideas that come out of a build to optimized energy recovery from a 30 deg C heat source.
I live in VietNam few degrees north of the Equator where we have a 6 distinct ethnic groups many of which live in reservations or defined areas.
The Government of Vietnam has done much to promote these groups.
Using this excellent video, a group of us have sponsored and built several systems in different parts of the country providing hot water and electricity.
A couple of projects were large water capacity and smaller electrical systems whereby a group considered water to be the more beneficial. The small electrical system is used to power water well pumps.
This series is so helpful in 2 ways: education and practical use.
Thank you so much.
I built a similar solar water heater for my outdoor shower using about 12 feet of 4 inch black PVC pipe. It provides hot water in the Pacific Northwest from March to October, and worked very, very well, to the point I had to caution people about the need to mix cold BEFORE getting in the shower. Adding a glass cover made it too efficient, and the high temperatures melted the PVC joints enough that they popped off from the pressure. Thanks for the video!
Now that's a sentence you won't hear often ,,too efficient" . Awesome Copper tubes with those crimp joints should Work. If you use a sooty flame (Carbon Nanotubes) to make the Copper tubes black it should be even more efficient due to copper and Carbon Nanotubes transmitting heat 1000x that of PVC
I have been working on adding cooling to the back of solar panels to cool them, hopefully to raise their efficiency on hot days as well as prolonging their life. The cooling will also provide pre-heating for my hot water heater and/or my pool. I’m also going to try to cool my house in the summer by cooling the house by running pool water through a forced air radiator in my house.
That's the way to go. It baffles me nobody is doing it. It's (almost) free energy after all.
@@xmtxx, I came upon the idea and developed some approaches. then, I thought to look and see if anyone else had the same idea. I found a few people who had done it or at least researched it and proposed methods.
Now, with bifacial panels that already have two sealed surfaces, it would be as easy as designing and bonding a cooling circuit to the back…
I’m working on one that bonds “U” shaped circuitous channels to the bottom glass. This would couple the water/coolant directly to the glass, as the cap on the “U” channels, making them tubes
Hey! Were currently building our house and would be really interested if you have any designs or links you are willing to share? 😊 Totally understand if not though. Thanks.
They do exist commercially, often under the term "hybrid solar panels", although they don't have a huge market segment.
I think one of the big barriers to adoption is that you need an installer who can handle both the electric and plumbing work, and it needs to be integrated both into the electric with an inverer, and the hot water system, which increases the cost at time of installation. I also don't think there's as many people/companies doing it, which also makes it harder to get right now.
Cool idea. Are there submersible PV panels? Would be cool to see how water depth over a PV panel affects efficiency. Would be cooler to see if that efficiency loss can be made up from extracting heat from the PV panels.
When I lived in Turkey these solar water heaters were very common, and in Alanya where I lived I only had about a week per year when the water was lukewarm the rest of the year the water was burning hot, a really great money saver.
This panel can put out close to 100 watts th-cam.com/users/postUgkxOqI2yqX0XVrhR2BMJciTWrHJpG8FhJyg when positioned in the appropriate southernly direction, tilted to the optimal angle for your latitude/date, and connected to a higher capacity device than a 500. The built in kickstand angle is a fixed at 50 degrees. Up to 20% more power can be output by selecting the actual date and latitude optimal angle.The 500 will only input 3.5A maximum at 18 volts for 63 watts. Some of the excess power from the panel can be fed into a USB battery bank, charged directly from the panel while also charging a 500. This will allow you to harvest as much as 63 + 15 = 78 watts.If this panel is used to charge a larger device, such as the power station, then its full output potential can be realized.
Solar water heaters are great for purposes like heating a pool or a camp shower, but what would it take to actually pipe the warmed water into a standard home water system? I suppose you would just pipe it in line after the hot water split off before entering your water heater?
A relitive of mine has a commercially made solar pool heater that uses what looks like a heavy duty version of black coroplast. A pump feeds water up onto the roof, and it then gravity feeds through the corrugations in the plastic sheet and down into the pool. I thought that was a pretty clever idea to get a huge surface area with a fraction of the material as a spool of pipe.
Don't you normally use them with heat pumps or something?
Rather than directly piping it in.
I have a commercial solar water heater at home with about 1.5x the size of the one in the video:
it uses a separate water circuit to collect the heat and then transfer it to or rather share with the hot water circuit/boiler of the home. becomes ultra hot in summer!
In winter, it is pretty much useless, as he said in the video
We use a heat collector thing and we have a tank in the cellar and I think there is a spiral in there that heats the water in the tank, it's not water that is getting heated in our system but glycol I think. In summer we usually reach like 100°C on the roof and end up with like 80-90°C in the tanks and that is plenty for showering and stuff like that
Yeah pool heaters are great, until they spring a leak and the pool is salt water :(
its generally not hard at all, you usually have a heat sink / exchanger before your hot water heater. they are just a water tank with a coil in them to pre heat the water before it gets to the water heater.
It would be really interesting to compare the resistive heating used in this video with a more efficient mechanism like a heat pump to see if that arrangement would outperform so direct solar heating. As far as I know a heat pump should be at least twice that efficient than resistive heating.
Great video overall! Enjoyed watching it
there is also geothermal heat pumps that have a Coefficient Of Power (COP) of >4. what if you combine both of them tho. PV to power the heat pump, and solar water heater to heat the coolant circulating through the heat pump. this would maximize the heating ability of the solar water heater as well given there is a greater temperature differential
@@Cracked1ce Sounds like good ideas for future projects and videos.
The guy in this video does a great job of being fair and explaining the actual real costs. Not some fake sales pitch. Also disclosing the issues of tax credits. Is it fair that someone that can afford a new car can buy an electric car and get a 7,500 dollar tax credit? Can someone making a mid to low wage afford new cars? even low end EVs 40,000 .
Came here to say this as well. Solar electric + heat pump might be a closer race.
Keep in mind, that adding a heatpump to the PV Array will increase the costs dramatically. So you should also expand the solar water heater Array to even out these additional costs.
Than you should compare the outcome.
And I think, you can easily quadruple the solar water heater array for the cost of a heatpump.
But that isn't an apples to apples comparison. The heat pump is capturing heat from the air which got hot because of the sun hitting the entire region of the country. The solar water heater is capturing heat from the sun that hit the box.
Was actually expecting a higher difference in temperature due to the inefficiency of PV. What id love to see is what happens if you leaverage the benifit of generating electric energy rather than heat energy, by for example using a heat pump rather than just "burning" the electricity. This would also allow for other sources of electrical energy like wind and water power to be used more efficiently. Also i think it is worth taking into consideration what happens once your water is heated. Especially thinking about seasonal storage here. Id love to see a future where we use the energy generated during summer to produce synthetic fuels that we can store and use to heat our homes in Winter
I strongly second this. Most air conditioners have COP of 2.3 to 3.5 (Wikipedia), meaning that you can expect up to 3.5 times the heating that you would from resistive heating as was done in this experiment.
If I had to future-proof, I'd also take into account the flexibility of electricity and the forcing function globally for improved heat pumps and more efficient PV. Solar water heating, as efficient as it is, could not be expected to improve much. I'd rather invest in infrastructure for the former, even at a greater initial capex.
Came here to say this. Heat pumps are the best way to use electricity for heating, including hot water heaters.
Good comment. Interesting. There are probably a lot of places that have AC or refrigeration and also need hot water.
@@mckenziekeith7434 any ideas on inlet pipe freeze prevention for off grid use?
I had just found your channel and wanted to say that I appreciate the way you explain the reasoning behind a choice and the technical side of what is being discussed. No hand waving or not going into detail. I very much so appreciate that.
9:04 upcoming aircrete video? Now that's a perfect fit for the channel, can't wait.
Basically "Every energy conversion comes with a loss, so less of them = more efficient system" Episode 2137
But it's only true if you're using that electricity to generate heat. It's not popular but I've seen homes with both systems. Collector for heating up water (or helping heating entire house in the season) and next to it PV for electricity production (for light, fridge and so on)
I think electricity to heat is more efficient than the other way around
This is the way.
@@CaneSugarHD Well, yeah, by much
Same here, plenty of places use both systems around Wadowice area.
Water to electricity I think you're talking about a Peltier device?
Excellent presentation. Very informative. I use solar panels to heat my water. I have dedicated 5.6 kW of panel's just to a large storage tank of 315 litres. I rely on the size of the tank to offset cloudy days of low output. It's not a perfect system but it's free hot water. I did consider a solar heater but roof space is not an issue and plumbing I prefer to keep to a minimum. I am a great believer in oversizing solar strings to offset low insolation day's.
Thanks for using clear, objective english. I work with a painter, and first job of the day is putting a 5gal bucket of water outside in the sun. By days end, we have steaming water to clean the brushes. I use the dashboard of my car to heat my lunch. It's a natural microwave. With me, you're preaching to the choir. All the same, keep the vids coming.👍
The system I'm currently designing for my house; involves a solar thermal loop, an insulated energy store.... and converting the heat to higher quality by use of a heat pump (powered by solar PV). As the heat source is above ambient, the expected COP should be far better than other heat pump solutions.
how does that compare to freeze storage systems (systems that take the heat from freezing the water)
I am wondering if it would be suitable to utilize the heat from a solar thermal panel to remelt the frozen store during the day.
The issue is with usable heat - on a sunny day, the same area of solar thermal would deliver more heat than necessary, but on less sunny days thermal alone can't create hot enough water for domestic use. The water from the thermal store isn't used directly (which avoids the complications of heat cycling sterilization) instead, the heat pump creates hot water on demand and can run from the grid (which in my locale is wind generation dominated).
@@DT-dc4br do you only mean hot water or heating. 🙈 maybe i have got you wrong. i was referring to heating, for which no sanitization would be required.
I meant that a store doesn't need to be hot but can be just cold water and the heat pump can extract the heating from the freezing water in the store ... the store would be underground and otherwise unisolated and except sludge I don't see why it couldn't be open for external water.
it's a concept sometimes used here in Germany (called "eisspeicher") ...
anyway i still am not sure how to reliably turn the ice back into water for the next night except naturally melting. solar may be a suitable low energy option to supplement this.
clarification: on our property there is already a water store that has been used differently in the past. however it is a little bit smaller and shallower than required so i would need to utilize it outside the bounds for a proper ice/freezing store and thus for very cold nights need a way of melting it back during the day... .
@@CM-mo7mv Both space heating and hot water from the faucet. If it's just for space heating, then lower temperature water can be used with larger radiators or underfloor heating...but then again, for most of the summer months when the system is getting the most energy... there's not really a requirement for it.
@@DT-dc4br absolutely ... that's why i am referring to winter and colder months ... I don't know which climate you are in but if it is anything like in Germany with sometimes quite chilly winters looking into differentiation in space heating and faucet heating.... for the later i calculated it may not even be worth it to have centralized faucet water heating as the power needed for that and much higher temperatures to be up to code plus the return path and capacity for higher demand ( e.g. taking a bath) results in almost the same amounts of power needed than full electric on our usage pattern and structure ... however i did not calculate with added solar heat during summer time yet (thanks for that pointer)
I got really into this a while ago and did some research on it. There were a few things that made me decide PV was the way to go.
#1. You use heat pumps to heat not resistors. So you can get a LOT more efficiency out of modern heat pumps & these things are going to be very reliable if you want to be able to occasionally use the grid to power water heating in the winter etc.
#2. You mention some of this at the end, but complexity in the solar heat collector for dealing with freezing and something you didnt mention - over heating. Over heating can be a big deal if you arent drawing the heat out for a few days during periods with a lot of sun. Industrial systems have pretty extensive solutions to deal with this that would add some cost to a home system if implemented.
There was a great article i read summarizing all this too - if yall are interested i can try to dig it up.
hi i will be glad to get it
I would be interested in the article.
Yeah I had all materials to diy a thermal heater, but freeze, over heat, and a lot of potential leaking made me decide solar electric was more practical.
A DIY over-heating solution shouldn't be to difficult.
Just a thermistor, two electric valves and a microcontroller.
And anti-freezen should prevent freezing, shouldn't it?
@@Jehty_ Yeah you need to vent it if it over heats, and I think you need to vent it near the top of the whole assembly.
If you use anti freeze, you also will need a heat exchanger to move the heat from the antifreeze solution to your house water. These problems are certain solvable, but they add cost and maintence issues, and you might not want cheap DIY things for a house you may sell... now that all might be fine but...
When you factor in the heat pump hooked up to PV giving you 2-3x the amount of heat generation as a simple heating element... PV really just makes a lot more sense.
Ive been building my own insulated panels for the last week now, heres to hoping they work in -25c. Wish there was a good way to share the progress on them. Either way its nice to see a scientific approach to showing the differences on many different aspects of what is truly a simple yet affective technology. Great video and look forward to more.
You have a TH-cam account. If you're willing to post updates on your progress, we can check it out.
th-cam.com/video/IM33OVCFK6g/w-d-xo.html
There is no reason that solar won't work at -25C, however here on Earth, in practical terms, that likely means besides cold temperatures, you likely also have low solar insolation (sunlight).
There are a few things I would love to see you test out. 1. Vacuum tube glass that is tinted dark or a beer/soda can heater. Both of these options are similar to your coiled pex tubing but I've seen them get extremely hot and move air using a 12v pc fan with a solar panel. I've even seen the glass vacuum tubing marketed as a solar cooker. Another thing I've seen is what's called a passive wall. Maybe not build it on your main home, but if you have a non powered shed that you work in, pick the side that gets the most sun during the winter and build a transparent box thats as air tight u can make it using greenhouse plastic tiles that look like metal roof tiles, on the outside and dark paint underneath. Inside this box cut vents along the top and bottom of the structure, protect it from critters with metal mesh and put one way air valves (like a piece of tar paper, cork or even adjustable dampers that flap one way only.) that lead inside the building, and on the bottom have it lead out to the greenhouse. The enclosed wall box would create a greenhouse effect and also generate pressure with the hot air that would blow into the building via expansion. As the air cools it gets sucked back out into the greenhouse wall and expansion occurs on a cycle. I've seen one person do this before on YT but you have a better channel to measure and collect data.
Passive systems are the best systems!
That is a version of Trombe wall. If the back of the box has high thermal mass (such as a brick wall) it can help keep the building warm into the night.
It would be really interesting if you ran the test with data logging, so we could see the water panel's efficiency drop as it heats up and at what point it becomes significant.
I think this would be the case with both... As the panels reach their max output the power curve will have a similar shape. But even more interesting would be if you had the data and could take the area of both curves to find the total power output of both and how they compare.
@@JonathanW5444 the pv output is not affected by water temperature.
@@pietersmit621 But it is effected by the temperature of the panel itself. I don't think it would be to the degree that the water heater's efficiency drops as it reaches it's peak though. Two different physics involved there. Still, there's a lot of data to consider there, with more instrumentation of course.
@@trplankowner3323 not just the temperature of the panels also the temperature of the resistors. these will increase in resistance as they heat up. this will lower the current draw and therefor make the panels less efficient as they are not in there optimal current output anymore. its one of the reasons why MPPT chargers are better than PWM ones. the MPPT changes its charge rate based on the optimal current draw from the panels
@@justingort1 While all of that is absolutely true and pertinent in certain perspectives. That isn't what I was referring to, I was agreeing that more data could be useful on this comparison. There's so many different aspects involved in this test that many could spend weeks or even months delving into the details. On each system. Still I think that the gross point of the comparison remains and is valid, much more energy is gathered by the hot water collector. However, if you need electricity and not heat, short of building a greatly more intricate system, stick with the PV panels!
It would be nice to see how a coil of copper pipe would perform in comparison with a pex pipe. Great video!
The Copper would conduct the energy at a greater speed than the Pex. However, since a therm of energy is permanent, it is going to move from high energy to low energy fairly efficiently. It won't simply disappear. The cost today of 200" of 1/2 inch copper tubing is around 750.00. The cost of the same length of Pex is around 105.00. Huge cost difference. And unless you require an instant heat, the added cost would be unnecessary because, the heat will find it's way into the pex. My garden hose laying on the ground gets hot enough to burn me when I first turn the water on. And, that's with no thermal glass, no box.
@@SUPERMAKFISH I just purchased 2 - 100 ft coils of 1/2" OD soft copper coils for $182 Copper tubing sales Browns Summit, NC.
@@SUPERMAKFISH for sure a house can be super hot and less costy if you store some thermal activity in good sealed tanks!!!! my next project!!!!! but not before instal some off grid electricity backup storage
Having lived off grid in remote wilderness (Almost 8 years) I have some thing to add to the comparison. The hot water is plentiful in the summer but in the north where we have long cold winters, -47c only the Solar panels produce and they do so with easily as the lower the temp the more efficient they are. It all boils down to where you live and the weather you have. I Still go Solar year round..
That's my plan for the farm here in central Manitoba. Solar pv panels all year round. Hot water collectors in the warm months & wood heat in the winter. And wood fired water heating in the winter. Which helps heat the house.
@@larryrobertstein7485 That is way to do it. I never was in a power outage because I had my own , just do 2 things, live within or below the power output of your solar system and keep the batteries from freezing( a fully charged battery will not freeze) my dad had a farm outside of Ericksdale Manitoba , small world.
This somewhat illustrates the difference between the theoretical and the practical. Starting in the late 80s and early 90s, various neighbors of mine began installing solar hot-water systems of this type while others began installing PV systems. Not one of the hot-water systems in my neighborhood is still in use because they always had maintenance issues and required monitoring and attention. The last one that I saw taken out was because a buyer of that house required its removal as a condition of sale. I have not seen that happen with PV. Most of the PV systems are still sitting here (often with a set of replacement panels) because they are very simple and reliable with little maintenance or further investment of time or money required until decades later when the panels are no longer producing sufficiently useful power.
Agreed. All the ones in my neighborhood fell out of use,due to maintenance as well.
THANK YOU, that is what i see all over here around me too; i am in Porto, Portugal ( that poor place where the INjustice system sucks big time, ask me how i know );
from my roof i have a clear view with binoculars of some 60 roofs at the same angle, and 15 years ago there were 10 or 15 hot water panels on them, and about 10 electrical PV panels; today i see only 3 hot water ones but 23 PV ones; my PV panels are about 10 years old,they have been performing great, no breakdowns at all,apart from the occasional inverter failure; luckily i can build them,and so,i have them modified to use main ICs in boards in sockets and it's just a matter of pulling one out and pushing a new one in,once every 2 or 3 years, they only cost 3 or 4 euros each,delivered from china;they are the famous SG3525+LM358 board for the first stage to get 380VDC, and the EGS002 board for the second stage to get 220VAC 50hz; coupled with the Lifepo4 batteries they run the whole house,not just the hot water;
Solar panels never breakdown, i never heard one one failing,it's just amazing,they last 20 or 25 years without fail; inverters are another story,but i use the cheap 150 euro chinese ones,they say 5000 watts,but they are good for 2500w all day; their 16 mosfets and their 4 IGBTs never braek down,it's the smaller boards,the control board ICs, that fail,and theey were sanded down by the maker,so i can´t replace them;
i now have 1 more new second stage unit ,an open unit,no box,no volt meters, of 3000 W or more continuous, a small monster with 8 IGBTS, that only cost me 52 euros delivered,and it uses the EGS002 board of which i have a few in stock, but this thing is so over sized that it probably will last a long time;
i get 2000 watts max (that is 200WH of elec juice every hour!!) from the Sun,from my 8 older panels,plenty in the summer,not enough in cloudy or winter days, when they only deliver 100 or 200,sometimes 50W and less; of course, near ZERO at night;
I'd rather deal with wires than with pipes thru the house, and most of the wiring was already there; and again, with a proper MPPT,LifePo4s,and inverters, PVs run the whole house from the whole March until the end of October; and some days in winter too at least partially;
I have a 24 volt system,i started small,less batteries, pity, should have been a 48 V volt; 24 V are good only up to 3000 watts max,and they require heavier wires that 48 volts too.
here in Israel everybody has a solar water heater (including apartments) and it works great
@@notajalapeno4442 Yes and no. The usual dud shemesh is still maintenance-intensive compared to PV, and it does not get nearly as cold there as in much of the US and northwestern Europe, which adds to the design complexity for deep-freeze protection and therefore more maintenance. Even in Israel, they have to have a variable supplementation system in winter in almost every application, which is more complex than just plugging PV into an existing electrical panel.
Before watching: absolutely a Thermal Hot water heater is generally far more "efficient" than Solar PV (as long as you want hot water, the energy source is much less convertible)
It is cool how the e-glass acts like a thermal "laser-like" amplifier
However on a cloudy day, its output drops to "zero" - well lets call it ambient, no gain.
Our hot water heater gives "free" - (Cost well and truly offset) hot water for 90% of the year, by Solar PV, offsets the rest of the power we use (Cash Positive).
An air source heat pump could give you a more comparable efficiency from the photovoltaics, but it would also raise the cost substantially.
@@garethbaus5471 : yes indeed, I haven't tested if the pump gain will make it as "efficient" as the hot water heater (a lot more complicated).... As previously stated, convertibility and tradability of electricity is the major benefit of PV... Also, the high price of Commercial Solar hot water heaters pretty much make them unattractive to install these days (PV plus heatpump hotwater heaters are most likely a better "financial" decision).
Next for TI to show home grown PV storage for flexible dispatch.
Keep in mind for the taxes, that solar panels would likely be more competitive without tax subsidies & incentives if gas and oil hadn't received many such subsidies as well (or at least received them in the past, furthering their development and infrastructure). I agree though and think we should get rid of all of them rather than fight fire with fire.
Very cool video! I'm really looking forward to more! I also agree with other commenters that I'd love to see a hybrid panel which uses the fluid to cool the PV panel
Thank goodness for oil. As we can not live without it. All you do, eat, sleep, medication, products, cars, and whatever is thanks to oil. This is something the oil haters forget.
@@flexairz True, but we can recognize how much its helped us while also recognizing the need to move on.
Europe hasn't had any incentive on oil and gas for decades. Last time there was anything like that was in the 70's with the energy crysis. Solar panels still only make sense because of heavy subsidies.
I'd love for renewable energy to become viable. I mean it's free energy for crying out loud. But they aren't there yet. Nor is there any sign that they'll be ready by the time politicians want to phase out fossil fuels. It's foolish to preach for the phaseout of fossil fuel before we find a suitable replacement.
Which to be fair nuclear power would be a more than capable replacement but if people don't want to use it then we'll have to wait for something else to be developed/perfected
@@tfwmemedumpster Oil and gas is renewable, it a mineral that regenerates from subsurface pressure of carbon and hydrogen (organic compounds only means it has carbon it in) this happens under ground to form complex hydrocarbons, before we started harvesting oil, oil would literally flow up naturally out of the ground.
it's less that oil and gas have been subsidized, which they have in some countries (read: globalization incentivizing oil and gas), and more that oil and gas companies can outsource costs onto the public. The cost of climate change is something that can be outsourced, the cost of people dying from lung cancer, because they lived too close to the coal plant, that's a cost that's outsourced. The incentivization of solar is meant as a way to combat the outsourcing, the "hidden costs", carbon tax is a way to combat global oil incentives.
An enjoyably informative video as per usual!
Just one thing: The PV panel table was slightly lopsided --- away from the sun --- perhaps reducing a few watts.
That said, producing heat from sunlight is easier than producing electricity. In equatorial regions, it's quite possible to even use the heat so collected to drive a steam turbine (I've read of and seen videos of companies doing this in places like the Middle East). But, for most places and especially in the upper latitudes, having both PV and heat collectors is best --- heat collectors for heating and PV for electricity (which can also be used to drive the pump in the heat collector).
My mother installed a solar water heater on her house in Arizona about 1975. It did an amazing job of keeping HOT water. She considered also expanding it to keep the house warm in the winter, but the cost of plumbing the house and a radiator in each room was prohibitive for the 4 months of the year that it gets cold (below 65 degrees). It lasted until at after 2005 when the new owners remodeled and removed the system. Solar electric was still a pipe dream in 1975, She was very pleased with the system. She figured it paid for itself in saved electricity cost in a little over 5 years. 25 years free hot water.
Wonderful video! I'm looking at building a hot water shower using a solar water heater at my off grid cabin (located on an island in the woods, in Sweden). This just convinced me even more that it's the right route to take. Though I will probably add some small PV or Piezo element to run the pump - since it only needs to circulate during daylight - when the heat is produced and than just let the hot water be in some form of isolated tank. With a Piezo one could also use the pump while the box is warmer than the outside, or double up with a water heater around the chimney from a sauna - or something like that.
Great tips on cost savings and where the most money can be saved. Keep up the good work, still loving the channel. Greetings from Sweden!
There are combination solar panels available, that do both PV and thermal in one. One positive side effect of this is that the PV panel is kept relatively cool, since high temperatures degrade performance somewhat. I've no idea if there are distributors of these in Sweden - I've not found much in Norway - but there are several companies in France, Austria etc. making such panels.
@@koma-k Great tip! Thanks a lot! Will look into it.
@@koma-k I've not heard good things of these combination panels. What was said is that the underlying thermal panels won't get hot enough and may leak, thereby damaging the PV. Your results may vary.
Have you considered a Stirling engine? Back in the 70's there was much talk of a thermal pre-heater called The Copper Cricket. I remember it was Popular Mechanics or Popular Science magazine innovation of the year. There were big problems in balancing the system, that required factory trained technicians. I haven't seen much of it since.
@@wilfredvanvalkenburgh2874 Can't say that I have, but I know of it. Probably a bit overly complex for this application, concidering others (less technical people) will use the system frequently, I try to have it work as "domestic" as possible - and automated. As far as I can remember, a Sterling engine needs a little help starting. A PV or Piezo just delievers power to an electric motor. Quite self contained system.
This was a great video but I’m really looking forward to the air-crete videos you mentioned. In particular, I can’t wait to see your version of a foam generator and your foam formulae because I think bubble size will have a big impact on strength and longevity, and that is where other experimenters fall short. Their bubbles need to be like shaving cream instead of like dishwashing bubbles. Also, a comparison of Portland-based cements to others such as high-strength cements (aluminosilicate cements?) would be interesting. A challenge: can you cast an air-Crete “board” as strong as wood that’s low cost (minimal metal)?
This guy right here is asking good questions.
We need the answers
Very much looking forward to air-crete videos as well!
Would be interesting but I think unless it's GFRC that challenge would be impossible.
Concrete holds well in compression, doesn't hold well in tension, while wood holds well in both.
I think in theory if you were able to create air crete with a solid outer shell, like a kit kat bar, you might be able to create something similar, but it's failure form and deformation would be very different from wood
On a similar theme - I find vacuum solar water heaters extremely facinating. The fact that you can get an almost boiling water out in the winter, when it is easily -15 C outside is amazing.
This is great. I get so many idea from your videos yet don't have the time to touch a fraction of it; I feel like I'm always playing catch-up just in terms of skills and time to get stuff done. Keep up the good work.
Hello! First of all, thank you for your amazing content. I am a big fan. Aside from that I work as an electrical engineer, building solar power plants. I am not sure if you adressed that on your video, but solar panels have an "optimum" operating point, that changes over time with solar irradiance, temperature and other factors. Normallly a controler is used between the panel and its load, either with PWM or MPPT tracking.
Keep up the good work!
Big hug from Brazil! 😁
I didn't cover that directly, but the optimal resistance for these particular panels under these conditions was measured and that is the resistance we used. An MPPT controller will accomplish the same thing automatically as the conditions change.
Thanks, I was wondering the same thing.
First thing: no MPPT on the solar panel? Second: if all you're interested is heating water, running an air source heat pump instead of a resistor bank off PV would have gotten you much better performance.
First: heating is by definition 100 % efficient, aka. the resistors are converting all the energy they get into heat.
Second: We're making hot water here, not hot air.
But, you're right. A heat pump beats everything in terms of "efficiency"
Agreed.
@@pugnate666 "We're making hot water here, not hot air" You've never heard of a heat pump water heater?
@@pugnate666 A heat pump can be 400% efficient compared to directly heating water with electricity
@@Ender_Wiggin my words exactly
I very much appreciate the fact that you mentioned the misleading effect that subsidies can have when it comes to making ecologically sound decisions.
Wait! You are suggesting that solar energy receives government subsidies and fossil fuel does not! Not to mention the cost of remediating impacts on global climate change.
The end user of any system typically makes their decision based on the apparent or adjusted cost to them. Each of the costs of material production, transportation, construction, and end of life disposal has an effect whether or not those costs are all reflected in the purchase price. Each level of government and industry may have fees or taxes or other adjustments applied that change the cost to the end user. Life cycle analysis is one name for the discipline that studies all of the actual costs of the use of materials and their impacts on society, the world, etc. Solar cell production and acquisition are affected by various levels of price support, subsidy, taxation, fees, etc, just like all of the other inputs to this system including the petroleum and plastic companies that create the tubing.
You people are confused about the intention of the subsidies.
You are right now currently not actually living a carbon emission free life. The free market says that you deserve to guzzle oil and it will be cheap. Living a zero carbon life is just more costly or inconvenient.
State subsidies are there because it spreads out the costs evenly. That's good public policy.
The negative effects of carbon emissions are collectively experienced so the costs to avoid the negative effects must be managed collectively as well.
@@rcpmac No. I don't see how my comment leads you to think this. It could be subsidies for fossil fuels, wind farms hydro dams etc. I'm simply saying that to make reasoned decisions we need all the facts and that they are frequently hidden or obfuscated by governments and other financially interested parties.
@@rasen84 The "free market" price of oil is an Illusion. I believe you understand that, but was not clear from your post. Gas and oil can be as high as $300 per gallon (combat zones), but the cost of burning oil, and the waste of plastics produced by oil, maybe the cost of our planet.
An excellent how to on a topic I know nothing about. The difference in collected energy was surprising, thank you for all the effort to prove it.
If you're interested, I can show you how to make an insanely cheap solar thermal concentrator that is >95% efficient at heating water, costs 1/8th the price of the solar water heater you built ($15 total for 1m x 1m), works in the winter, and if insanely easy to build. It uses a vacuum tube as the collector, 1mm acrylic mirror sheets as the parabolic reflectors, and a copper heat exchanger to pipe water through. Very similar to the parabolic concentrators that exist today, just made for 1/50th the cost of commercial oil fed units. The temperatures inside the vacuum tube easily reach 600-800F, even in winter, almost none of that is radiated away (because of the vacuum), so all of it goes into the water. I've built several versions myself, got lots of pictures and parts still lying around. Very simple design, just 2 sheets of acrylic, one bent into a parabola by tension, plus 2 side pieces that hold the vacuum tube in its position, assembled by hand in seconds, no tools required. Would love to show you how it works.
So show us, make a video!
Corn chipsian
I've done this experiment myself: When it is really cold out and you are wanting hot water, the temperature delta is going to highly favor the PV. The efficiency of it goes up as the solar cells get colder, while the flat-plate is going to fall dramatically as the delta between outside and water temp increases. Even evacuated tubes can no longer keep up.
This is exactly what I am concerned about myself, otherwise, I would have done it also. PVs are also good to generate electric power for everything else as well.
I read an article of a home heated by water run over black aluminum roof panels.
This provided hot water for the home and also heat for forced air heating. The hot water was collected in a 1600 gallon container in the basement. The water tank was surrounded by large rocks, then a layer of insulation. Air was blown through the air spaces between the rocks to heat the home. The fuel usage in Virginia dropped from about 690 barrels of heating oil to about 90. I think this was a journal article in Solar published in the 1970's.
Enjoy your shower and dishes. I love all your videos, but mainly the distilling is what I like. Hope you have a great week.
You're doing the lords work. Im about to start building your foam speakers for me living room. Thank you for doing what you do.
Lord Kelvin!
The what? Lol
no, you dont have to do work, at all, and not for people, at least
@Hot Sausage I dont earn my living, I'm given to
You need to add a evacuated tube collector to the comparison.
We wanted to demonstrate a system you can easily assemble yourself.
It's pretty close with the 2 panels of glass. You could vacuum between the layers and put argon in to improve it, but it isn't going to make much difference until you are below 0.
I wouldn't think the thermal mass of the enclosed air would make much difference. Remember he covered the water panel to prevent preheating it, and it still outperformed the PV panel as the air heated up along with the tubing and inside paint and so forth.
If anything the enclosed air helps equalize the temperature of the tubing from end to end. Plastic tubing doesn't like temperature differentials very much.
Speaking of temperature differentials- early panels used copper tubing, likely because it was relatively chap at the time and much easier to work with than stiff plastic (and is UV proof unlike the PVC tubing used in early non-copper versions). Copper tubing also transfers heat through its wall better than almost all plastics meaning it heats the water faster than plastics. It still needs a good flat paint though as it's a fair reflector of heat.
@@jmaus2k You cant pull a vacuum on such a large flat piece of glass, it will crack very quickly. If you just want to replace the gas in it, you'd just flush it with gas instead. Probably not worth it though.
@@markfergerson2145 The vacuum in the evacuated tube collectors is there for insulation. Just like in a vacuum insulated termos flask. Thermal mass has nothing to do with it. With the air in the collector like it is now you conduct the heat trough the air to the glass, and right trough the glass to the lower temperature outside. While with a evacuated tube collector you only loose the radiative heat out to the glass, not any convective or conductive heat loss like you get with the air filled collector.
An evacuated tube collector would preform a lot better than the DIY collector he made here.
I've looked at making these. I would probably put some form of insulation, maybe spray foam, to help with the cold colorado winters. I would like to see how the antifreeze would work against regular water or salt water if you rather not use antifreeze.
One downside of these is the time it takes to heat the water. 15L isn't a lot compared to a standard family water heater. I would be interested how quickly water heats in an open system as opposed to the closed system you made.
These are very popular in Greece. They are on nearly every roof out there.
These techniques and systems are not just at lower latitudes. Heat (and “cold”, collected during winter) storage tanks are also common in the Netherlands - using large temperature range liquids - or so I was told when I was doing (unrelated) engineering work there. I wish I would have asked directly, but my interpretation of this at the time was that the systems were probably using ethylene or propylene glycol. Superior insulation is obviously, absolutely essential. The way it was explained to me, with the system continuously being heated and with the volume being large, the efficiency and utility ends up being quite high. Naturally, energy is still harvested at some rate, be it faster or slower. But, I guess the overall point is that it can be practical, once the scale of the system is sufficiently large. Although I have no information to substantiate this, I suspect that systems using this technology are also using small demand heaters (electric or natural gas) to boost the tank temperature water up to that which would be used by, say, a bathroom shower.
Edit: …along with antifreeze/tap water heat exchangers, if that wasn’t already obvious. (Maybe the demand heaters and heat exchangers can sometimes be integrated? I should look that up…)
Typical antifreeze/s offer a significant advantage for heating/cooling systems that use pumps or convection to regularly circulate water: they significantly reduce corrosion/galvanic reactions. Even though those reactions are fairly slow, they do create abrasive precipitates (for example, aluminum oxide - commonly used to make sandpaper) that can easily cavitate, and therefore destroy, structures in the system over time. I’d stay away from salt water all together, for this reason. Although I thought it would, we found that using distilled water (as opposed to municipal water) alone doesn’t help all that much.
A friend made a system long ago. It uses discarded uPVC double glazing panels and discarded domestic radiators. The boxes were also made from waste and recycled material. An small electric water pump was purchased from a scrapyard. The only things he had to buy were the pump, hosepipe, insulation materials, paint and support fittings. He is in central England, and has almost never needed to use his electric water heater, even in our coldest weather (about -10°C), for over 25 years.
I hope you get a chance to build a pop can heater. I built one at 4x8 ft. and it tripled the ambient air temp outside. I also moved the air through it with a 5 in. computer fan driven also by a solar panel (12in.x16in.x7watts). It was easy to make with simple materials. I used a 1/4in. 4x8ft. sheet of plywood for the base. I made a 4in. side using 1x4in. around the perimeter and lined it with chrome bubble wrap. The top was covered with a clear plastic normally used to help insulate windows, and a second layer placed over top of wooden bows of wood cut to 1/4x 1in. to give it a better insulating factor. The bows were slightly longer than 4ft. so they had about a 3 to 4in. lift in the centre to hold the second layer away from the first. The pop cans were easy to prefabricate by using a can opener on the tops and a hole drill to open the bottoms. I used 100% silicone to glue them together placing them in a long piece of angle iron to keep them strait till dry. As it is currently outside in the snow, I cant remember how many rows I put on each side but it was an uneven number, like 6 rows on one side and 7even on the other. Now don't be confused when I say there are two sides because what had done is built a 4x4in. plenum at each end four ft. wide at the top and the same at the bottom but it is divided in the middle but only in the bottom plenum. So now the air comes in through a 5in. hole drilled in the bottom on one side of the split plenum it then goes up through 6 rows of cans held in place by 2in. holes cut in the upper and lower plenums. Then comes out the top into the upper plenum and goes across and down the other 7 rows into the bottom plenum then out through the 5in. hole and is exhausted out the 5in. fan. In an country where it gets extremely cold in winter months, this unit will work very well as supplement heat, as long as there is sun, which I don't get through the winter months up here in Canada. Ya so it was a bit of a waist of time. Truth is I just have too many trees and not enough sun. Thanks for all you cover in so many videos, sincerely Bill Campbell. PS sorry if I misspelled anything.
now use a heat pump with the pv panels :D and yes cost goes up but so does efficiency :D
"cost goes up"
then the comparison isn't fair.
everyone knows if you want to increase efficiency then the costs go up. so obvious
@@lordjaashin yes but over the life of the product(s) it might be cheaper and also with a heatpump with a cop of 5 you get a lot more out of it. so a test of the roi with a heatpump involved aswell would be interesting
@@niklasxl the problem with heat pump is it needs to be run on grid electricity. it cannot run on PV panels unless you have huge array of panels, battery banks and MPPT controller.
it might be more efficient than solar heater but what benefit is the efficiency when its high price turns away majority of customers?
@@lordjaashin it's totally fair if you want to.maxomimisr heat and have a fixed area but unlimited funds. you also need to consider what the costs really are, if you have a large installation, say a 10kw heat pump, that's a huge number of panels, the extra cost of the heatproof over 25 years isn't so much.
On the other hand if cost is the limiting factor nit space for panels, consider that for say 2500 bucks you can get a different area of thermal vs. Pv panels.
Being in Australia and trying to keep the heat out of buildings, I'd be very interested in development and testing of a DIY barium sulphate based paint. Lots of recent research showing benefits, but sadly no products on the shelf yet.
DIY is the route. don't make yourself dependent on corporate vultures and wait for them to rip you off with products that you can make your self easily
And if you live in tropical environment in this project you can eliminate the insulation (glass) and leave the tubes exposed. If I had to build one, I would use two reservoirs, one on the roof and one underground, to have thermal insulation on colder days or long rainy periods.
I purchased a house in south Florida with a solar hot water system that "didn't work". A small amount of tinkering, mostly replaced thermocouples, and air purgers made it work again. I only ever turned on the electric backup in December and January. Water temp (in the tank) ran from 120 to 180 degrees. Yes, I installed a thermal mixing valve. Most of the people who removed those systems didn't want to be bothered with maintaining them.
If you're putting the solar thermal system onto your roof, remember to account for the extra weight involved. You might need to reinforce the roof rafters.
My roof is cement, but thanks nonetheless
True, but don't forget most of the water will be in an insulated storage thank that's not on the roof. A 100 feet of 1 inch ID tubing would only hold a bit less than 4 gallons on water so you are only looking at about 35 pounds of water.
They suck. Solar hot water was very common in the US before natural gas and oil and to a lesser extent bottled propane were cheap and available.
They don't really work very well unless you live in the deep south and have lots of sun available most of the year.
A lot of the efficiency of the system is lost because of anti-freeze. Direct heating is just a lot more efficient than adding a heat exchanger. They just aren't very good at transferring low grade heat (when there is not a very large temperature differential between the antifreeze and the water you are heating.)
That's pretty silly. I have 13 12ft by 4ft solar panels to heat my pool. They don't weigh much full. If you are scared of your roof, the thing to worry about is how much things contract and expand. Even a rubber boot will wear a hole in shingles in under a month. A bit of flashing under contact surfaces solves that.
@@tarstarkusz your generalizations are misleading. I have a well designed solar water heating system which uses a heat exchanger and propylene glycol antifreeze and water mixture, in Ontario, Canada that continues to work well 14 years after installation. On the other hand, I'm pretty sure that there are poorly designed products out there that do suck but that doesn't mean the technology itself is the problem!
13 seconds in and I just punched the air and yelled "YES!!".
I'm glad this topic will be explored in the level of detail and care you put into your projects.
@@1newme425 Where did you get the jump part from?
I was searching for "e-glass" but found it to be the high electrical resistivity fiber type glass for electrical insulation.
Then I learned something:
The reflective-coated thing is called "low-e glass" and there are two very different types of it:
- "Passive Low-E Coating" is an Indium Tin Oxide layer designed to gather as much heat from the sun without letting the heat out
- "Solar Control Low-E Coating" is a thin silver layer designed to improve thermal insulation both ways, it is used in hot climates where it doesn't let too much heat inside.
The former is obviously the best for this project, while the latter might even be counterproductive.
This is quite an interesting topic, it would be interesting to see how it performs when it's cold outside or when the water gets really hot. How much does power vary over temperature (difference), at which point is it the same as the PV panel.
As for the PV, its efficiency is much more consistent with a constant voltage than a constant resistance load. Around 75% of the OCV.
Anyways, great video, these things always get me curious!
I have a 9.6 Kw peak grid tied pv system to replace some of my electrical load and a solar water heating system to replace some of the propane gas fuel cost. Both systems do not replace all of my energy loads, but, they definitely do help. I am located 30 degrees north of the equator in north America and we get a LOT of sun most of the year. Might as well use it, as it would otherwise just heat the roof of the house. The solar water system is 25 years old now and I have had to service the panel on the roof once and just replaced the pumps in the heat exchanger this year. Set for another 25 years, I guess.
Thanks for all that you do and introduce our younger generation to the application of science.
It would be interesting to see an experiment where you want to see how much stored Kilowatt you can achieve, between the two sources you have, which is PV panels verses solar water heating which is converted to electrical energy. What I notice in your experiment, is that the solar modules needed to be placed correctly as to the azimuth angle to the sun to optimize the efficiency of the pv array. I have both systems at my home, where I am totally independent from the grid for both electricity and water heating. Each on their own are excellent in their own application. Your experiment was very interesting, and makes one think. Thanks.
That’s what I’m thinking!!
Hey Nicolaas, i see what u mean, but, wouldn't putting the solar water heater also to the correct angle to the sun make it more efficient thus giving the same results as the video? IDk it's just a possible asumption, although maybe due to the way a PV panel its built the angle affects it more than i think idk or event maybe once the water heater stars to reach a certain temperature it just reaches a limit where's maybe the PV panels start to have advantage. (Also the water heater is slightlly bigger in the video but i think he said he had it into account)
Sorry for my english im spanish.
Since you mentioned aerated comcrete (aircrete), do check out aircrete with shredded styrofoam, for budget insulation. The video "Aircrete on Steroids, Aircrete Styrofoam. Build Cheap" by "Stephen Williams" says that adding shreded styrofoam to aircrete makes it 80% as thermally insulative as normal styrofoam of the same dimensions. Also, I wonder if using cooking oil instead of water would make the solar water heater just as easy to pump and not much worse in used thermal capacity. For example, some motor oils freeze at -20 F or -28 C, though they might be too thick for a solar heater, but it might be useful to consider some other thermal liquids, even if their price is higher. Or maybe adding metal powders, like you did to the thermal paste, would help by increasing the thermal capacity of the liquid after the antifreeze lowered it. At that point, the problem would be to make sure the pump isn't damaged by the thermal liquid, but taking all those things into account might help find some other more-efficient strategies. Another thing to take into account could be using stainless metal sheets to reflect more sunlight onto both the solar panels and the solar heaters. "Sergiy Yurko" has a video called "Very cheap ( $15-40 ) solar collector-concentrator that does not need a tracker", in which he shows how specifically to make steam having snow on the ground, using concentrated solar, and while solar panels need to not have their temperature too high to work properly, they also stand a lot to gain by concentrating sunlight onto them in the colder seasons, while the solar collector-concentrators only need a different thermal liquid to increase their working temperatures significantly, and motor oil might work wonders in that case. Sergiy Yurko has calculated the price for the heat of concentrated solar to be about 0.5 cents / kWh in the latest video, and other similarly small prices for other setups, in his location.
Antifreeze would be better with a heat exchanger or heat pump... to heat the building
Aircrete Styrofoam - Stephen Williams is a new up and comer aircrete channel that he shows measurements / results, unfortunately harry has not been posting that often as of late.
Sergiy Yurko - such an underrated channel
Wish Tech Ingredients will also look into Rock Stove and Rocket Mass Heater. Ive seen a lot of designs but I think Matts is the best
th-cam.com/channels/XnaWrIqSe7BgrlD14zUFAw.html
he is very helpfull and friendly.
Its quiet a unfair comparison. With a Solarpanel you get more exergie, which can be used to power a heatpump instead of an resistor. This would give you more heatenergie when the heatpump works with an Coefficient of performance of 3. I dont say this would be cheaper. If the solararea is limited this would maximize the heatoutput to win your test.
I don't think it's fair to use a heat pump's thermal coefficient as justification for the inefficiency of the PVs. Following that logic you could plug a light bulb into the PVs and say they're infinitely more efficient at producing light than the direct heaters, which would be true but completely meaningless.
The point of the video, as I understood it, was to compare the solar energy collection efficiency of the PVs with the direct heater panel, not to compare how the energy is used, which is why resistive heaters with their near perfect energy to heat conversion are ideal.
@schutz nhil Turning electrical energy to heat energy is the most efficient thing he could do here. Claiming higher efficiency with a heat pump is not accurate at all- assuming a motor drives the heat pump (~60% efficiency), you still have to transfer that thermal energy from the air to the water (using more motors at ~60% efficiency.)
A resistor array is 100% efficient in converting electricity to heat. Nothing is more efficient than that.
@@SytheZN What i am trying to say is that sure you gain a bit more energie by using the waterheater, but the type of the energy is far worst.
@@LeObsidianCraft 100% is nearly a low bound when trying to convert electricity into heat. For sufficent small tempratur differential of course, like we have in the test.
The nice thing about solar water heating is it can be economically scaled to the size you need. Our farm had a tin shed the size of an out-ous with a black 55-gallon barrel on top to heat water for a shower when coming in from the field. Being 60 miles west-north-west of Wichita Falls, Texas a black barrel was good enough for most days in April through October. It was built before 1947.
I helped a neighbor near Frisco, Texas heat his pool in 1972 by laying a 3/4'" black plastic pipe on his roof and running the pump with a switch on a solar cell that turned on in the afternoons with enough sun. The pipe drained back into the pool when the pump turned off, I think it cost $60 or $70 bucks. It was still in place a couple of years ago.
Another great video! I'm sure you've thought about this, but it would be interesting to do a DIY Sterling engine build (or something similar) to see how efficient electricity production could be from the heating panel. It certainly won't match the PV panel efficiency, but could be worth considering once you take into account all the factors
It might! We can't really know without actually getting the Sterling engines or other thermoelectric generators into place and testing them in real-world situations as in the video above.
Would like to see you build a phase change energy storage unit to go along with your panel! Thanks for the video, great to see a comparison!
With an eye towards maximizing the use of a rooftop, how much heat can be extracted by water-cooling the photovoltaic panels from below? My understanding is that the PV panels are more efficient when operating at a cooler temperature?
To start it would work as good as both of the system but as the water under the pv panels heats up the panel loses efficiency due to it warmimg up past whatever temp it would have been with ambient passive cooling
First of all, thank you for your excellent explanation and good images of the technique. I myself have a finnish house , sawn and custom from Finland . I live in the middle of our country . construction was completed in 1980. At that time, we were already aware of the necessity of being finite, ie becoming more expensive for energy, from the ground up. I used much more insulation than was supplied and also prescribed. Later I bought a used water tanning heater. of 7 m2. with a storage tank of 250 liters , also a still working one . Heat pump for shower and drinking water heating. Inh 300 liters . Shortly in 2013 16 PV panels, Mono Crist, 4400 kW per year. and shortly a heat pump air water air . for my hot air heater.
I used for this house of 13x14x9 meters high and a basement of that size area. around 1200 M3 gas. and 4400 kW of power. per year . Now I'm testing my house without gas. I did the test for my Hot air heater with a New WP Boiler (175 liters) which is now available as delivery. of shower water running with it. it turned out that my 35 KW radiator that I bought to do the test . With my Midea heat pump I can heat the house with an average of 400 W. energy from the PV panels. A whole story. but without being able to heat gas in this horrible time with that Putin war . Makes me feel good . Read the book " the black gold " 25 years ago . confirmed that I was right to make all these savings. I am now 75 years old . and healthy to do everything an older man can do in his life .
thank you again for your excellent contribution to all the problems we face .
Sincerely, Giel Klaver
Hulsterstraat 2 4116 EZ Buren ( Gld ) The Netherlands .
Thank you for this video. Our combined knowledge comes from our combined experience, and your experiments add to the pool.
It would be nice to see the final numbers, specifically time and temperature gain.
It's hard to conduct such experiments without any bias, for example: the hot water panel is insulated, and thus prevents heat loss from the water that circulates inside it. On the other hand, the pipes leading to and from that panel are not insulated, so there's unmeasured energy loss there... hopefully all the small biases cancel each other :)
I wonder what we'd find out if there was another panel which combined both approaches, i.e.- heating water with the excess heat from PV panels, which uses more of the light's spectrum, and at the same time cools the panels, which increases their efficiency, would the extra work and cost be worth it in comparison with the simple water heating panel?!?
Also, I think such experiments need to account for the intended use of the system, since converting one form of energy into another, (electricity to heat, and vice versa), involves some energy loss, plus an added cost/complexity to the system itself, and to its maintenance.
Regardless, your experiment seems to show that the gain in energy harvesting efficiency is far greater than the loss during energy conversion.
Thanks again.
Umm dear idgit, there are NO PIPES to a PV panel... there are WIRES. The solar thermal collector is at the disadvantage.
I'm glad you covered the benefits and costs of both systems thoroughly. A blended system is certainly best in the right climate.
I live in germany, and like many here i have solar water panels on my roof, in my case 20m² of Flat panels ive installed myself. You got a bonus from the gov for changing your heating system to condensing combustion + solar system at the time when i did this. My oil consumption significantly dropped because of these changes. I have 1m³ water Tank I heat up using solar & oil (which is only fired when the top section of the tank falls below 50°C). Later i installed a water jacketed wood oven in my living room, which allows me to heat my house with solar and wood from around late february to december, only in deepest winter i use the oil to compensate.
Would i do it again? well, maybe not so much... The heating system is very complex and with that big solar array on the roof, in summer i have gobs of heat, i have to dispose of, otherwise the system ends up overheating and breaking. My godfather has had a solar system with photovoltaik panels installed in 1991, which is still running at around 75% its new peak power 30 years later... and he had very little problems with it so far. Using modern panels together with a heat pump you get similar heat output as the thermal system and have the advantage of gobs of elektricity in summer which you could use to run an AC, maybe charge an EV... Even home batteries are getting cheaper so you can store it. And: On a cloudy day, my thermal panels arent collecting at all, while a good photovoltaik cell is still collecting 15-20% its peak power...
You can cover the panel fully or partly, and then it won't heat.
@@jaejohnson4631 Yes but you have to take into account the very harsh environment on a 50° direkt south facing roof. Covering it by hand is challenging/ dangerous, could only be done seasonally + most materials dont live very long due to intense heat& UV. Far easier to just keep it running and dump the excess heat.
@@tiboreeb5360 the time would be early morning before sunrise, after it has cooled overnight. Of course covering a hot anything is not a good idea, although I have seen people make adjustable shade systems. Also it must be covered in white, no other color, which can be conspicuous.
@@jaejohnson4631 you dont understand... that roof sits 7Meters above ground and has a steep slope. you wont do anything safely without a scafolding. And the problem with the material isnt that the roof itself is hot, its that whatever you put on that roof will endure extreme temperatures and UV during daytime. The tiles reach far above 100°C, and even a white surface will get scorching hot. When i was installing the system, i had to wait for cloudy days, because when the sun came out, you litterally had only a few minutes until you cant touch stuff with your bare hands without getting burned. And yes, you can build motorised shadings etc.. but as far as i have heard, its expensive and very high maintenance.
@@tiboreeb5360 I see. How are you disposing of the excess heat?
My suggestion may not be useful in your case, but I hope others reading this thread for ideas as I did might find our suggestions/warnings useful.
Great job! We are at Capricorn tropical line. A few decades ago (1970's energy crises), my dad decided to build a solar water heater. It was a interesting introduction to energy balance and engineering for me, at high school at the time. The colector had 2 by 4meters, it could suply with very hot water, 85oC, enough for the needs of a 6 person house. We had to be carefull with hot water burns.
Counting disposal as part of the overall cost!! This is one of the reasons I really enjoy the videos on this channel. Plus twenty years from now one of these two systems will be running the same as ever.
Also looking forward to the aircrete episode. Hopefully EPS beads/chunks in the mix will be considered?
Please note that this is highly dependent on which panels you get and their warranty.
Tier 1 panels are warrantied to still produce 93+% of their rated power at 25 years.
After that, they fall off 0.30% a year.
If you're running a single solar panel, this might be an issue.
If you're running a 5kW system, not so much.
Basically at 35-36 years, you'll have just hit 90% efficiency.
Note that, depending on your location in the world, your system may actually over-produce by a few percent as well.
Which could take some of the bite out of the performance degradation.
You could also opt, early on, to simply tack in a few extra panels and/or storage.
You may also find out that your consumption actually goes down over time as more energy efficient appliances enter your home.
Not sure if the heat collector will make it 20 years, especially not with strong sun and weak maintenance and frosty winters, but yes it’s better long term stable than the PE panels
Interestingly in Japan, disposal is included in the cost of many devices, such as computers, and they come with a sticker you need to have on the device when you hand it in for recycling. (I have never actually used this since I usually sell my devices while they still have some value left).
how is the channel not past 1 million? I've been watching for a couple of years already, love the passion for information you guys have!
I think it's because it's not flashy like other engineering channels, and the videos are long format. Sucks, because it's so dedicated, humble and thorough, it gets less views and subs
Most people have learning beaten out of them by public education. It has to be flashy and not require cognitive thought.
Thanks for sharing, Always find your videos interesting and well made. From a solar hot water sight a few years ago that sold the vacuum insulated glass tube water heaters. They were located in Binghamton NY and said the infrared sun light makes it thru the overcast winter sky and makes hot water year round. Always thought it might be interesting to see if a solar hot water driven sterling motor powered generator might stand up to a photovoltaic in the winter.
But secretly I figure if anyone can build a residential sized thorium LFTR it’s you guys.
any ideas on inlet pipe freeze prevention for off grid use?
@@mangeload they only have water in the pipes and collector headers, typically they use a glycol mix with a heat transfer at the water storage tank, I believe the glycol not only prevents freezing but increases heat transmission. They also have a gravity drain back tank with the pump driven by a solar panel, if there is enough daylight to run the pump it’s assumed the heating panels are also ready to go.
@@tbix1963 Thank you for your response. I have an idea (im sure im not the first to think of it) to run a low watt (3W/foot) 12VDC thermal pipe trace on a thermostat that controls when the trace is actively heating, which is also thermostatically activated so it will only heat where / when needed. The purpose of this setup is to prevent pipe freezes while minimizing power consumption in an off grid system. This will be efficiently accomplished by avoiding an inverter's idle draw, and maximized by running low consumption DC pipe trace & bypassing inverters altogether. This should be a practical and inexpensive way to prevent pipe freezes (much cheaper than new plumbing) & will provide a small backup supply in case of emergency power outage, that can be easily built upon. And I'm doing it all for between $500-$600.
Here is my planned setup:
100 amp hour deep cycle battery, 40amp MPPT charge controller, 100w mono panel, cables & wiring, connectors & fuses, 400w inverter, 6 - 8 feet 12VDC thermal pipe trace (@ 3w/foot 18w-24w), thermostat, pipe insulation, & maybe a battery bank status monitor.
Future plans also include 600w total solar panels combined & 4 x 100ah deep cycle batteries, & a 1500w pure sine inverter. What do you think? Any advice or suggestions will be appreciated.
@@mangeload maybe I misunderstood your problem, you have a water source that your afraid will freeze? If you have plenty of water that is pressurized a cheap solution would be a freeze miser water valve. Under freezing conditions it allows a small flow of water keeping the pipe above freezing temp for the price of some water. Freeze Miser, can be found on Amazon for about $30. I’ve seen it used by ranchers in subzero temperatures to water cattle from garden hoses lying on the ground.
As for your electrical solar solution, I’m no expert but it sounds like your possibly going in the right direction. I’ve used heat tape before to winterize pipes in a drafty cellar before but always found them a bit unreliable, compared to letting the water trickle. Good luck with your project.
My wifes dad a well driller 50+ years ago designed a rooftop Cooper tubing box that heated up by the Florida sun. It used no electricity only gravity flow. Guess he was way ahead of his time. It worked great too, and STILL WILL
I would expect to be the heat-only collector to be at least 5x as efficient as the electricity to heat one - assuming a 12-15% efficiency in the pv panels. But electricity is so much more versatile than heat...
5x is a bit high for a ratio between PV and Thermal collection. If the PV panels are 17-20% efficient then to by 5x the thermal collector would need to be at least 85% efficient... Which is asking too much from any conversion device, let alone a home brew water heater. 3x would be more like it... Also, inadequately addressed is this: as the thermal panel warms it re-emits and, low-e coating or no, it has a nice big eye looking up at the cool sky for radiative exchange (aka thermal loss.) Hotter collection means hotter emitter and lower net efficiency. It is still higher than the PV but not 5X.
This demonstration is a good start but, as you mention, the versitility of electricity (it can be converted to light, computing, entertainment, heat and even money) means it can tolerate a less efficeint conversion process because its product is more economically valuable. But like the host said, if you have a thermal load you know you are going to serve.... thermal collection is a great way to go.
Yes, I didnt even understood why they were comparing this.
@@gamingSlasher The idea of reducing it to one common measure (Temperature rise) is good as far as it goes. Isolating to understand is a great practice. But they fail to do the other contextuaizing work to help viewers get the big picture. (inpart creating the chaotic mess that is the comments stream below.)
They are trying to make the argument that we should serve heat loads with heat collectors (for efficiency) and us electric collectors for electric loads. There is a bit of free market rah rah thrown in. ( I think it is more complicated than just some customers paying for others to enjoy solar, but this is kind of extra off hand contextualization which is where we all get caught out extrapolating beyond things we have deeply thought about.
You covered a bit the topic of harvesting radiated energy. In the previous videos you covered the topic of the cooling by liquid evaporation process. What about the cooling process by emmiting far IR radiation into the sky? You mentioned the film that alows the visible light to come through the film but doesn't release the IR outside. Is there a film that releases far IR instead of light/near IR?
Would you consider the efficiency of the LPG system? I know it works decently, and you know this as well. I think lots of people from the audience would benefit from such knowledge. They would listen if it could come from you guys.
I originally determined to skip to watch just near the end. But turned out I keep scrolling back to a bit earlier that where I started again and again as you keep giving some very interesting info that I have to scroll back to see where it come from
Dang what a channel
😀
Here's a project idea for ya... use solar hot water to boil something like pentane or something with a similar boiling point in a closed loop system in order to create a pressure that can either turn a small low pressure turbine or even a piston of sorts to generate electricity. Pentane looks like it should produce around 75psi at 100c which could drive a small turbine, or maybe better yet use low speed opposing pneumatic pistons to turn a shaft. Larger pistons can create a lot of force even at lower pressures as long as you can create enough volume and not allow the temperature to drop much until the vapor leaves the pistons. Worth a shot! And to anyone who doesn't think 75 psi is enough to do anything (compared to say high pressure steam turbines) take a 6 inch piston for example... at 75 psi it has a force of about 2120 lbs.
Stirling engine ?
This wouldn't give you much. In the best-case scenario, you will get Carno cycle efficiency ((t hot) - t(cold)) / (t cold). It will be about 20-30%. So you will go below the efficiency of the PV panel.
@@Shmidtk an opposed piston engine would almost double that efficiency!
@@fabriglas Is right. Use a Sterling engine to take advantage of the high temperature gradient between the water storage tank and ambient air. You'd insulate the entire storage tank except for the one spot the Sterling engine makes contact with the surface.
it would be super interesting to see this redesigned to use a fresnel lense
All that matters is the amount of sunlight, which is proportional to the area. A lens would only help if that lens is bigger than the solar collector and then concentrates the light onto the collector--in which case you could simply make the collector bigger at probably lower cost.
I have a four foot square fresnel lens and although it concentrates intense heat in a very small area, it does nothing to the area outside the focal point. Also it is very directional and has to track the sun or it doesn’t work. You can melt lead or even concrete with it but it’s not practical for many other purposes.
@@sandyt4343 Maybe mirrors would be a better option then
I would be curious to know the absorbance of the solar collector, as in what percent of the solar energy is actually absorbed, and how much is reflected from the paint, or absorbed by the glass.
Based on solar panel would be near to 20% efficient and the solar heater increased the temperatur about dobbel, the total should be around 40% efficiency.
Best commercial PV extracts about 23% of available insolation.
Best commercial solar water heaters get more like 75%.
If you heat your water with electricity it usually makes sense to install solar water heating before going for the PV, but check out the costing before you do.
Love that you even included the pump's specs !
Using both systems would be preferable. I’ve seen a lot of houses with sun heated water, but they are always disassembled because no one wants to maintain them.
Maybe you might like to explore solar ovens with different material incl aircrete as content especially in New England to show the power of gamma radiation being converted into thermal! You can put solar concetrating fold out wings on it too. Very interesting subject and so many great ideas i have seen! 👍🏻
Hope he considered it
I'd love to see a related series on DIY heat-to-electric conversion. Maybe optimizing DIY, medium-scale Stirling engines?
I haven't heard of any efficient way to do that at small temperature differences. There are places that use lots of mirrors over large areas to drive generators:
@@AmbachtAle The Carnot efficiency limit for a ∆T and max temp of 100°C (373 K) is about 26%, so a really well designed Stirling engine driven by this could be competitive with photovoltaic panels. Or at least be in the same order of magnitude.
@TechIngredients
I just bought a small house in a remote area in central Texas that has high electricity cost. We even have high LP gas cost because we are remote. My current water heater is old and expensive to heat water. I'm going to supplement my hot water with this type of capture system. This could even supplement a small sub-floor heat system for my bathroom too.
Thank you for your great instruction and solid inspiration.
You're welcome!
To everyone saying “why not use a heat pump water heater”. Yes, a COP of 3+ is typical. However, these pull heat from your house and it becomes a rather convoluted comparison.
If the house has a net heat load (hot/summer) then this is extremely efficient and takes load off the AC.
If the house has a net heat loss (cold/winter) then you now need the heat from your primary heat source. If that is gas/resistance/heat pump, we’ll you’ve just moved the actual heat source to that system.
I think this is an entirely fair test. As someone in commercial HVAC, I rarely see heat pump water heaters. Electric resistance heat, I see all the time. It’s definitely the predominant electric water heating technology used.
This. I think heat pump water heaters are great for people who have the $2000 to spend and never mind the tank has the same warranty as the $650 gas-fired unit. Problem is I live in Michigan where electricity is 14 cents per kW-hr and nat.gas is 87 cents per therm.
Now what I love is technology designed for DIY and longevity. You find me someone who grafts a heat pump onto one of those fantastic old monel or copper-tank water heaters from the 1940s (never rust!) and you'll have my attention.
Friend of the family has a cabin up north with a Lochinvar water heater from 1957. Works great. Blows my mind.
Agreed.
Something I've always wanted to do is add Peltier plates to the backs of PV cells, since they'd be in the sun all the time, and the cold side just leave ambient. What do you think?
You could buy electricity until the end of time before you make a profit on pelter elements, probably the most inefficient way to cool or heat, but to create power...
You're better off pedaling a generator
You can get solar panels that are double sided, you can just generate more power from the sun reflecting off the ground.
You'd spend less energy just driving a pump for a water loop.
Assuming the PV module is operating at high efficiency it wouldn't be getting too hot - idk though
Another fantastic video, first thanks for the intricate detail. In regards to cost and societal cost and subsidies, you should nor forget to mention that keeping greenhouse gases down is in fact more important than any short term inconveniences from subsidies. Of course that total life cycle (environmental) cost is the important one.
Just a reminder that 100 companies produce over 70% of all greenhouse gases, this would make no tangible difference even if adopted in a large scale
As a plumber, I can testify that getting 300ft a PEX pipe in a tangle has brought me to edge of tears!
Me: *Building PV-system at home*
Tech Ingredients: "Should you really use solar panels?"
Me: "Oh, that's interesting, let's see!"
TI: *solar heater*
Me: *lives in Finland*
You do that then.
What is the surface-temperature of your panels? You may be able to squeeze a few extra % if you force-cool it. The warmed coolant is a bonus. Adding antifreeze will be a pain though :( What do winter temperatures look line in FI? -40'C ?
as if solar panels work better in Finland lol. you should have said "you do that then" for solar panels too
You can make a heat exchanger on the inside of your house like he said in the video, and run antifreeze + water in the main system. Even in subzero Temps it will still heat your water a little bit, enough for your main heater to use less fuel.
@@lordjaashin For serious production yes. Most of my power comes from a couple 300w wind turbines, but solar panels are quite useful for about 6/12 months of the year.
@@AdityaMehendale -40C is a rare occasion. It's something that your home should be able to sustain once or twice a winter. -20 to -35 in norther Finland is the usual business.
Thank you for sharing your insights to this project like the metallic glass and the camouflage spray paint you used. I really enjoy your technical presentations in all your videos. I am toying with the idea of building a greenhouse and using passive solar heating either with water or circulating heated air into the ground to extend the growing season. There are many videos on youtube about passive solar heating, but I have yet to see anyone speak on the technical details such as the rate of change in temperature of the thermal storage, be it for water or soil. I know this is dependent on a number of factors (you mentioned insulation or the ambient outside temperature). In the case of heated ground, depth and the type of soil. clay versus sand versus rock will have different characteristics in thermal storage. It's great that people are posting videos of their builds, but they never mention the technical details such as volume of thermal medium required to keep an n' x m' sized structure warm. I would be very interested in knowing what you would come up with as a solution and your technical analysis.
Mhm "if the system doesn't make sense without subsidies..." but if one considers the ecological cost of burning coal and natural gas, which has been displaced onto the future generations to deal with? Who pays for it now? If it's politically impossible to introduce a kind of tax/insurance/fund which will cover it, maybe solar subsidies are the next best thing.
How hot does the PV panel get? Is it possible to harvest the heat from underneath it for water heating? Would it provide some cooling for the panel, raising its efficiency?
Obviously you can't get the circulating water particularly warm, or it wouldn't be cooling, but maybe if you have a sufficient resevoir of water to where it won't get very warm, you have still harvested the energy and you can then electrically heat it up a little more on demand.
"if the system doesn't make sense without subsidies..." isn't the US already subsidizing power production? Federally, to the tune of ~$15B a year to oil and gas.
Well prepared and presented. I currently have a 1800 watt PV system sublimated by a 1000 watt wind turbine. My summer home is located in northern Arizona. The elevation is 7500 feet the home/cabin is 1400 square feet I use 4 rolles surrett lead acid 6 volt batteries 450 amp hours each wired in series’s for a 24 volt DC power supply. I take the 24 volt power and I use a 4000 watt power inverter to provide 120 volt AC power
I saw one video where someone compared PV to pumped water. The result seemed to be that the pumped system worked better at lower temperatures (like up to 40 degrees), but when the water got hot (or didn't get very hot) the PV would continue heating the water until the tank clicked off. The pumped water kept losing heat in the collector and pipes and never did get the water up to "hot water tank" temperature, 55 to 60 degrees. In addition, a few hundred bucks for a couple of big solar panels (350 watts each, these days?) and wiring it up is incomparably easier than piles of plumbing to a "pre-heater" tank that feeds the "real" hot water tank. I did that in 1979 back when there pretty much was no solar PV. Not again! You have extra pipes and an extra tank to leak and replace, freezing issues and a pump (needs electricity anyway, albeit little power) to wear out and fail. There are "Dernord" electric water tank elements for various voltages and powers. I got a 1200W, 36V one for a 15 liter tank under the kitchen sink on my 36V DC system, but to avoid overpowering the solar on cloudy days, I wired 2 of the 3 "U" loops it had in series for 200W. (It did reheat pretty slowly.)
I would use hot water collection for cooler water like heating a swimming pool.
I installed about 350 solar water heating systems in Wisconsin between 1978 and 1983. They were either anti-freeze or drain-back systems. Some large arrays of 50 or more, but mostly 3 panel systems with a total area of 63 square feet. The boxes were aluminum, with about 1" of fiberglass insulation. Absorbers were nickle plated copper, and laid out in a reverse return pattern. The absorbers were anodized with a "selective surface", as developed by Everett Barber and had such low emissivity that a single pane of low-iron tempered and non-reflective glass was used. In full sun when the systems was running the glass was cool to the touch.
At the time, we calulated that it would take 5x the area, and 7x the cost to duplicate the energy produced by the solar thermal system.
Great video and effort. Having a thermal water panel still installed and working for 21 years without problems -just replacing the outside pipes isolation-, nowadays, I would choose a PV.
Why?
In summer, we have lots of hot water that we don't use, just 2 hours with sun are enough to heat the 250 l tank, and we are "loosing" all the other sun hours by harvesting anything at all. But, we still need to use electrical power for the recirculation pump to avoid overheating of the solar panel and pipes.
Instead, when heating water using a PV + heat pump you can increase the performance x3 or x4, (better that the test you did that was about x2 better performance on thermal vs PV) and once the water is hot the PV panels can be used for other appliances (oven, PC, TV, air conditioning,...) or sold to the grid.
PV vs Thermal panels drawback: higher initial investment (inverter, heat pump,...)
PVT (Hybrid PV + Thermal panels): at least they can use the built-in PV to power the recirculation pump and at the same time to cool the PV for better performance. But I still would invest in a PV+Heat pump system.
Excellent video, thorough methodology and really helpful. I had no idea one could make one's own solar water heater panel so cheaply! Thank you very much.