I am a retired electrical engineer, and I see a lot of misinformation surrounding solar systems on TH-cam with content providers mixing up power, energy, efficiency, and capacity. You did a great job here! This information is very helpful for people trying to size their systems. Thanks!
Well I'm in the solar industry and I can tell you you are 100% correct. I tell people to ask the sales person what the difference is between power and energy and if they can't rattle it off the top of their head then kick them out the front door. Then there are some guys that are so confident they talk about capacity of a battery bank in K dubs. It irritates the hell out of me! Or the newspaper talks about a huge generator installed and it makes 30 kW a year. 😂. I asked them if they have a water system that produces 60 psi per year. 😂
I'm amazed... Someone on the internet who actually knows the difference between power and energy. I started googling this stuff and found that more than half of the hits were people talking that clearly had no idea. Thanks, this was super helpful.
My rule of thumb for anything you want to run pretty much off the grid indefinitely is to take your daily device power consumption for a 24-hour period and multiply it by 3 to 5 to give you several days of capacity in your battery bank in case of a string of cloudy days or snow-covered panels in the morning. This usually gives you a good base to carry through even a string of poor solar days. Then add enough solar panels to be able to charge your battery bank in 1 or 2 days from empty to full. This size of system will only use a fraction of the storage on a typical day with decent sun but will still have enough capacity that you don't need to babysit it all the time when the weather is bad.
I got a 300 ah Ampere Time with the last of my savings and a charge controller and inverter so I can have at least some power for a small window air conditioner after hurricanes and to save some on my electric bill since I`m on SSI disability and utilities may skyrocket cutting into my small check. I live in a 5th wheel camper so my bills probably won`t ever be too high but I just moved in. I have solar power stations for other things like a freezer, dlorm fridge, and smaller stuff.
This is good advice and i wonder why more people don't also run a windmill, there is heaps available, they work well and we use them at sea. However i assume it's noisy in suburbia but off-grid means remote, imo.
@@rasta77-x7o There are generally stronger winds 'at sea'. Rule-of-Thumb is an average of 13 mph wind is needed to justify a wind gen. And that's NOT common. I bought a 500 watt WG dirt cheap; and my area does NOT a 13 mph ave. But when it does get windy I want to take advantage of it.
One other significant point. The more you oversize your batteries vs daily draw - the longer their life span will be. There's no free lunch with physics but equally investment up front and IF You can avoiding heavy loads (C rate) will pay you back.
I have four of those same batteries in my shop that has no power otherwise. 6 100 watt panels keep them up just fine considering I use the shop mainly on weekends to scrap cars and other metals. I can run a sawzall, 12 volt LED lights, a fan to circulate heat, chargers for cordless tools, and whatever else for the entire weekend. These batteries are exceptional for the price. I've never had any issues.
I am so glad I found this channel I live in the same area and I am just starting my journey into me of a self sustainable way to power my home. I didn’t follow all of the logic, but I will be returning to this video until I do. Thank you.
This was VERY helpful. The only suggestion for dummies like me is that you just round up from, say, 485 to 500, even if it's less accurate. The whole numbers make things easier by far! But yes, I watched this twice and hit rewind a few times, and it was much easier to follow than many videos on the topic. Thank you1
Thanks for the kind words! Making videos like this for TH-cam is often such a tight-rope walk...I know that if I over-simplify, I'll definitely get comments that I'm not being precise. So yeah...I try to walk that line and find that I'm rarely successful. hahaha Still, I'm glad you got some value out of it. :)
This is the information that you NEED above all else! You NEED to know what your usage (rate of consumption) is over time. No other info is as important. You can now set up minimum and maximum usage over time and choose the capacity of storage that is needed! The Watt mater is the best tool in the arsenal. How are you supposed to know what you need, if you don't know what you consume? This is the area of solar power that people need to become educated in!
Use of the refrigerator as a reference, and project is brilliant! So many folks throw up random information which doesn't correlate to real world needs.
One of the best things you can do if you live totally off the grid is to use as many smaller 12v appliances as possible, so you only have to turn on the inverter in certain situations, saving quite a lot of power, and therefore money.
Easier to design and live around a system based on 48 Volts. More power, less copper, and when it comes time to run AC appliances, you won't have to play the power rationing game. You can add a 48 to 12 Volt converter to power your 12 volt buss. Electrical Food for Thought...
This is probably the best video on solar for non commissioned solar officers...please ..since you are so gifted..make some more...very real ..very simple..and i will call Ampere time for a very big order for my projects...simply because i believe you...
Great video. To me, it is all about using the AC, refrigerators, heaters and other high end energy consumption items. This will tell me how to set up my system.......Based on a little bit of luxury camping. Boondocking in the high heat or winter is why both AC and heaters are needed. Maybe having solar and and inverter generator would be a good back up. All this seems EXPENSIVE!
I’ve got 700 watts of solar and two 30 amp charge controllers feeding a 200 ah Ampere Time Lifepo4 battery. That goes only to a 5,000 watt 12 volt inverter. It’s plugged into the shore power for the trailer which feeds 3-125 ah sealed lead acid battery’s . Should I use a generator or actually plug into shore power the cable is unplugged from my Solar inverter system. It’s fused and has breakers from the panels and to the lithium battery. I spent last winter in the Quartzite/Yuma area. The lithium battery worked flawlessly and I never had a single problem. Your calculated system requirements helped immensely with my purchases.
Wow ive watched so much on solar and batteries and always was confused, you made this so simple to understand i truely thank you soooo very much , simple math and explained perfectly....im working on a 17 foot camper and want to start gathering my electrical system components and you helped me tremendously.....thank you very much
Excellent video! I am a huge fan of solar and understand that you need to balance your expectations. My purpose for solar is backup power, and I determined first how many panels I could support, then purchased mostly 12v items, including a dc fridge that could be supported simultaneously by the panels, then purchased batteries that were 4 times the capacity of the load during a 24hr time period. This will give me 4 days of dc fridge, lights, fans, laptop and phone charges, and various small electronic recharges. And I have a Honda i2000 that I plan to top off the batteries daily and intermittently run ac appliances like microwave and toaster oven. If real world testing shows I have power to spare, I would like to add an inverter as well to lesson my dependance on the generator.
Great point about 4 days of power, you would hope to get some sun every 4 day cycle. I know the 24v fridges are bigger than the 12 v, I wonder if they’ll surpass 12v sales and popularity. Still considerably smaller than current mains supply fridges, but perhaps two would do the job? What is the capacity and price of your battery system please?
I like the Edison type batteries because you can run them down very low without damaging them, and on top of that you can maintain them and even refresh them later into new batteries by switching out the acid. You can still get these types of batteries from China and Russia. I plan on getting a big battery bank, solar panels, invertor and backing it up with a couple small Honda propane fired generators and a very big propane in ground tank. I want a 12,500 gallon tank so I could go 10 years if I need to on the 10k of propane in it. If we get set back to the stone age, I want to be good for 10 years even if I do nothing else for supplies outside my property.
@@jasonbourne1596 when does propane go on sale? Generators can be run on hydrogen. 10yrs food supply could take up a bit of space. Secure, and environmentally controlled storage. Need to think of intruders/invaders. , , could be a sizeable meteor, that intrudes...lol Have fun 🎯😎☕
That is one of the easiest explained breakdowns of such a relative and common query, that I am agasp! Thank you kind sir for the time taken to do that for folk like me.. yur neighbors in , IN!
For offgrid use i use a 9cf 24v refrigerator and a 10cf 24v freezer. Using 3 200watt panels, the system works great using 4 100ah agm batteries. With enough reserve to go a couple of days of fog. Great video.
But with agm is you want your batteries to last then you should only take them down to 50% depth of discharge which is 12v. So realistically you only have 200ah
@@dirtydog288 with the refrigerators i don't use an inverter. They're 12v. I do use a 1000w inverter to run lights at night and a computer during the day.
I went off grid ten years ago and built my own home single-handedly. In June 2021 I bought a Tesla model 3 and wanted to charge it using the sun. Here is my setup: I have three 300 watt panels. I have a flat roof and leave them flat as I live in the middle of Oregon. (If I tried to point them south I would only get rays between 11am and 2 pm.) On a sunny day I get almost 800 watts. I feed this energy into a 60 amp MPPT charge controller keeping six 100 amp hour Battle Borne batteries charged. The key is using a 3500 watt inverter (pure sine wave). On a sunny day my Tesla wants 1500 watts if I set it to 12 amps and get 6 miles of range. On a cloudy day I need 1000 watts so I change the Tesla charging down to 8 amps and get 4 miles of range. I use thick wires so I do not loose current and protect batteries and inverter with 300 amp and 200 amp circuit breakers. If I tried to use 12 amps it would drain the batteries real quick so I keep it at 10 or 8 amps and it charges for 14 hours a day. This actually is as good as if not better than someone on the grid using 120 volts AC. Make sure you use a bonding plug (connect neutral to ground) if Tesla won't charge. Some inverters don't need one.
Exceptional video! Each calculation was explained very clearly. Whenever folks start to contemplate their needs in terms of solar panels, solar charging capacity, battery size, system voltage, inverter sizing and losses, as well as distribution (110 vs 220), it tends to be very surprising. As you have spelled out in this video, it takes quite a bit of equipment and expense just to power a residential refrigerator off of solar and batteries. When you throw in those extended periods of poor solar conditions, and the equations for how many more panels and batteries are needed to account for that, it becomes clear that staying grid-tied, if you can, makes a TON of sense. Thank you for doing such an excellent job with these videos...they are far better than most!
It depends on your local cost of electricity, but solar usually pays for itself. Home battery backup doesn’t unless to have loads that you want to ensure never get interrupted. Here in California with our cost of power and the issue of taking power delivery out of service during high winds was enough for me to get a Power Wall. I have an automated system that keeps all my critical loads powered whether I am her or not.
@@sjagain I would guess longer than the batteries will last. Everyone else I’ve watched says you need about 3 times the amount of watts used per day. To cover for the days of no sun. So, suddenly we are talking $6k worth of batteries. You not charging those with 600w of panels. I have been running numbers, I need something like 65k worth of batteries alone to go “off grid”. We use about 60kwh per day 🥺
@@MrTruck1012 Well since these are LiFePO4 batteries they should easily achieve 15 to possibly 20 years of service before calendar aging completely takes them out. They will likely never see the number of cycles to kill them in solar duty before they fail due to age. The main thing you have to decide is how much you really want to run since a system that is being used to keep the fridge and or freezer on all the time could also power all or most of the lighting circuits in a modern house that uses LEDs along with a couple outlets without adding much more if any additional capacity and would really come in handy when the power is out. The batteries are expensive but there are ways to get by cheaper if a person wanted to DIY a system with raw cells and a BMS or 2. Used solar panels are sometimes sold dirt cheap. I bought 24 used 345watt panels for my system for ~$3800 that were only installed for 9 months and were about 1 year from Date of Manufacture. I paid $150 per panel plus tax. So if you look you can often find deals on craigslist and facebook marketplace on panels. Going off grid won't be as inexpensive as being on the grid, especially if you buy a fancy new system with all the bells and whistles and have it professionally installed but if you start small with the goal of just keeping a fridge and freezer on plus a few lights and maybe a couple outlets you can often put a decent dent in the electric bill while also providing you with a bit of backup power when the grid is down. I power my entire house except the range and internet equipment from a single 6000 watt split phase inverter that cost me $1200 about 2 years ago, Along with 3 X 60A MPPT charge controllers costing a total of $435, a ~375Ah 16S 48V LiFePO4 battery bank built from raw cells Measured capacity is a bit over 19.5KWh for ~$4500 with 3 BMS units included (I could do this slightly cheaper now). Water heater conversion to 48V (~$220) in parts and wire. 24 solar panels for $3800 plus about $200 in fuel to go get them. Ground mount solar array using heavy duty galvanized unistrut $1300. Various wire and cable along with fuses, breakers, busbars, shunts and conduit ~$2600. All totaled that comes to a bit under $14,300 not counting my time but it is a hobby after all. In the past 2 years I have been almost completely off grid except for the electric range and my fiber internet CPE, router, and 2 access points. So I have already saved a bit over $2100 off my electric bill. While I don't expect to get much over 15 years total out of the battery bank, it could happen. I expect the system will pay for itself in another 12 years or so, maybe less considering how much electricity has gone up in the area. At that time I will need to buy more batteries and possibly a new inverter or charge controller. The biggest benefit so far has been that in the last 2 years we have had 3 local power outages, all from bad storms 2 times were only out for a few hours but one of the 3 the power was not restored for nearly 3 whole days and during that time I didn't even notice except the internet and cell service throughout the area was down.
I'm glad I found your video. The way you explain how solar works and what you need to make it work helps me to understand it all better. I'm sure I'll have more questions at a later date.
I know this is an older video but youve just made an entire video on something i keep bringing up to myself in a quest for a small DIY solar setup ive been building. Of course you need battery capacity to run something while there is no sun...but you ALSO need enough solar generation to run said item while there is sun AND have enough surplus to bring your battery back up to a 100% SOC at the same time. You are the first person ive seen to actually bring up this real world way of having solar. I didnt find this out until well after building my system. Had i known before hand, i likely wouldnt have spent money on 12V only inverter and would have well upgraded my charge controller as well. At this point im doing all i can to make things work with the several hundred dollars i have invested into a system that is almost maxed out.
One more addition needed here and it's the idle current draw of the inverter. Normally when the fridge is running it cycles between on and off, and the off state draws almost zero power. Your inverter standby power will still be drawn during this time and this can add up to a large amount of watt hours quickly even though there is no load.
Absolutely correct! 💯 I was thinking that my rounding things up would have mostly offset that, but it's a real thing and probably should've part of that walk-thru. So thanks for mentioning that.
A lot of people scale too low or they talk about whole house systems and never define the proper total capacity. Your example was simple, explained well, and scalable.
Great video. Something that got my attention a few years ago was when I plugged a Skill 7 1/4 inch worm drive circular saw into a 2 kilowatt gas generator. The saw draws 15 amps at 120. Volts or about 1800 watts. Should work. What I forgot was the extra energy needed when I pulled the trigger. Yup killed the gas generator. (I've been using the Kill-a-watt units for years, great product.) It's not just the running power.
Took me a couple days to figure this out all on my own starting from zero knowledge of solar. This video would have helped big time a few days ago lol.Very clear and concise. In TX, in these past 90 days of 100+ weather the AC makes my daily usage 75,000 watts...Im gonna need a ton of batteries lol.
During the day you will be pulling straight from the solar panels and not the batteries! Batteries are for when the sun isn’t shinning(nighttime) or when your pulling lots of power beyond what the panels can do
@@thomascranor9505 During the day my ac plus other utilities hover at around 5,000 watts/hour, how many solar panels would I need to keep that going from noon to 6 pm? What about rainy days and cloudy days? Also I don't want to backfeed the grid ever so that's why I want to stay on battery use and storage only.
Enjoyed the lesson, thanks! Your example is very practical too; keeping a refrigerator running is probably the most critical need in a long term power outage situation. One positive fact which significantly prolongs the battery’s watt hours, is that a refrigerator does not need to be powered 24/7 to do it’s job. During long outages here in eastern NC, to save fuel, we will run our generators 3-4 times a day for 3-4 hours.
@@SomeBuddy777 another power saver....I'm from Florida but now live in South Louisiana. Between me and the in laws we use a bunch of deep freezers for fish and game. Freeze clean 2ltr bottles of water and keep a few in freezers and fridges. It helps reduce cycling. We do it year round. In the event potable water is in short supply you can thaw them out.
I purchased two, 200ah Ampere time batteries, and I Love Them. We are on day 9, without plugging in, With 420w of solar. Best investment we made. I may build a few power boxes with their batteries at a later date.
Very nice and clear video. Unfortunately, at 7:50 you are completely messing up the units. The only unit that is sort of correct in this equation is 'h' for the duration of the test. The usage is not 6201W. It is 6201Wh, which you then divide by 38h (lower case h!) to yield 91.2W. *Not* Wh! The unit W is short for Joule/second, where Joule(J) is a measure of energy expended. So energy use is measured in Watt multiplied by a time unit such as hours. If anything, the outcome you are trying to get to is 91.2Wh/h, also known as 91.2W
It bothered me a lot to see this unit mess and was pleased to see that somebody actualy pointed it out thoroughly in the comments. It seems to me that so many people just can't get their head around the difference between units of amounts (how much) and tempo's (how fast).
It’s a good idea to make all your calculations based upon winter performance when the number of daylight hours are lower and the sun is lower in the sky. If you can, use solar trackers to maximise the output of each solar panel. On my journey with playing around with solar, I ended up dehydrating lots of food for a food storage solution so I am not dependent on my fridge freezer if I can’t generate enough energy from solar. I grow my own vegetables as well so when it comes to dehydrating veg, it’s useful that there is still plenty of sun at harvest time to use my dehydrator. Everyone should go on this journey to appreciate the power consumption of various equipment. For me it changed my mindset when purchasing new electrical devices. I usually look out for power ratings before I look at the features of the product, and whether I can power the device directly from DC. I also try to make sure if I can power any device directly from DC, I’ll power it from DC. A mistake I see in a lot of You Tube videos are people powering or charging DC devices (5v, 12v, 18v) using AC to DC adapters. They don’t seem to understand energy losses in converting DC to AC and then back to DC. In my eyes, it’s bad practice.
Hi. I would agree that it seems pointless inverting up to AC to convert back into DC for many of our devices. Have you considered whether the loss in the inverters is more or less than cable losses? For example, I imagine running 12v the length of your house to power LED lighting would have quite high voltage drop unless using fairly heavy cables. It may be worth taking the hit converting it to 240AC so you don't lose as much in the cables. I suppose 110V in America would be slightly less beneficial due to the lower voltage but just wondering if you had worked it out as its something Ive always wondered about?
@@davidleisk580 I helped a friend wire a DC circuit around an old derelict house in the middle of nowhere powered by Solar. Plenty of sunshine and plenty of land. We rigged it so there was a main battery bank (48v) charged by the solar panels. Depending on the requirements around the house, we stationed various secondary battery banks around the house for various purposes, some battery banks were 36v, some were 24v, some were 12v. They were all automatically charged/topped up by the 48v main battery bank. They all had isolator switches. Upstairs lighting was on one circuit, downstairs lighting on a separate circuit, ‘workshop’ had a separate circuit to charge the cordless tool batteries etc. We didn’t bother calculating efficiencies into wiring decisions, we just designed a solution which we thought was practical. There were numerous reasons why we decided to have secondary battery banks around the house, one was simply to increase energy storage capacity. When the sun is out, it doesn’t take long for the main battery bank to become fully charged, meaning you are losing energy which can be stored. It makes sense to use the main battery bank to charge all the secondary battery banks so you can take advantage of sunny days. Another advantage of having secondary battery banks is that each station is independent. If the main battery bank disconnects because it’s reached a low voltage threshold because let’s say the workshop has drained it you still have energy stored in your kitchen, lighting and living room secondary battery banks i.e. the lights don’t go out even if the main battery bank is disconnected. In summary 48v main battery bank wired to each secondary battery bank. Each secondary battery bank has isolator switch plus a solar charger/regulator to auto top up from 48v main battery bank. Don’t know if that answers your question in a round about way.
@@davidleisk580 The 5-15% efficiency loss in the inverters, depending on which brand you have, is almost always far more of a loss than the voltage drop found in the great majority of cable setups, even those running the length of a house.
On my sailboat, this year I replaced two - 4D AGM batteries with two 12v x200amp Ampere Time Lipo batteries. Before the final install I couldn't get the batteries charged up to capacity. I contacted support through email. They were prompt with a response. I was just impatient and just needed to let the batteries charge longer. So far everything has been fine and haven't had any issues. The weight savings is unreal! Those 4D's are hernias waiting to happen.
The way I understand charging batteries is the speed of charging is related to the difference in voltage between the battery and the charger. So when getting close to full it just takes longer.
The battery's ability to charge is another important constraint. Ampere Time specs a MAX charge rate of 100A, but if you want to get the full life out of the battery, you should use more like 20-50A. If other decisions drive you to a 3 kW solar array, for example, then you should realize that a pair of these batteries will only handle 12.8V x 100A x 2 = 2.56 kW at 100A, or half that if you want to prolong battery life. We sized our system to cancel out our utility bill, for example, and then got the minimum battery capacity needed to charge under full-sun.
Very good explanation,the guys who supplied my 2400 unit . The installers did not actually know how to connect, despite having a circuit diagram. I had to show them
This is extremely helpful! Easy to understand and well presented with a focused message. I'm planning to set up offgrid power to my machine shed and want to run lights and maybe an outlet to recharge tool batteries. But now I can likely calculate what I would need to run a corded saw. And I'm surprised at the price of that battery. Two years ago I converted a cargo van to be a camper and used one $300 96amp hour glass matt battery. Lithium batteries were $1000 at the time. I really should upgrade to LiFePo. Thanks for your post!
love ampere time batteries I have five that I use for several dif setups also Eco Worthy batteries have been good for me as well completely satisfied with mine
Great job. Thank you for sharing. Now let's look at the 10 year de-rating curve for the battery to include that 20% reduction and reduction of solar panels (-20%) efficiency add 50% more battery capacity for beyond 10 plus year coverage on your battery requirements. De-rate curves need to be included so end of life for that system is extended. Peace and blessings to all. ❤❤❤
It;s a decent battery. Just don't let it freeze--no low temp protection. That said, I made a 600 AH system with their 200 AH batteries and a 4000 watt inverter. Works AWESOME! Best part is it's not a sponsored 20k battleborn/victron everything build.
@@alexkennedy5133 You can. But I installed them in behind my 5'th wheel's kitchen cabinets directly under the bathroom. It's a heated otherwise unused dead space that houses the furnace and water heater, and therefore stays warm all year.
I've looked at solar several times over the past few years, a nd by "looked" I mean: I looked at a few websites and videos and got frustrated and quit looking... After viewing this video, I really feel like this is very doable. You did a great job, my friend!
On the refrigerator example some Modern refrigerators have a heating element that operates during a defrost cycle and that can raise the refrigerator power consumption to over 700 Watts for a period of time. That should be calculated into these measurements.
Your video is very useful and you explained very well. I would like that you consider a video adding a fuse to the battery and any fuse you may consider necessary. You have the ability and the skills. Your video is A+
First off--excellent video! If you will be using a Kill-a-Watt to calculate your avg requirement you'll need to multiply it by factor 1.2 (min) because the 485 watt avg daily solar for your panel is based on current at the panel itself, before being conditioned and stepped down to charge your batteries and/or be inverted back to AC for your appliance load. So each 92 watts through the outlet requires at least 110 watts of solar production at the solar panel leads. Conversely, 12/24v chest freezer (which can be used as a fridge, too) is really the best way to do this "indefinitely" . You will only need a small charge controller, one 250w panel and one 100ah 24v battery. The daily consumption of a 12/24v 9cu' freezer is less than .75Kw, and less if it's in your midwest basement at 65F*ambient. You'll use about 500watts of your 2500watt battery capacity (DOD--20%) daily, so it's ok to go with an AGM in this particular case, and still have enough storage for a three -day total eclipse! 😃 Plus they have very thick insulation(4-5" walls) and will stay cold for at least two days after total loss of power.
We have 2 separate systems. The first is 200 watts of solar panels, 1200 watt inverter, 200 Amp charge controller with about 450aH battery storage. The second system is 9- 15 watt panels, a 400 watt inverter, and a 400 watt charge controller with 105aH battery. Also a 20 watt panel, 45 watt charge controller, 150 watt inverter with about 2-35aH batteries for charge-way radios and phones.
Great video, thanks! The only one small mistake I see (maybe somebody already mentioned that) is that wattmeter detects only refrigerator working time, but sometimes it in idle mode. You need to calculate the time by your own and then calculate an average consumption based on that time. So you don't need so big battery to support it.
Thanks for the kind words! But thinking maybe you skipped some parts? I actually explain that in detail starting @6:30 so the 100W per hour that I'm using is rounded up from 91W per hour - which is the calculated average consumption my refrigerator uses (from the total of 6201W over 68hrs sample period). Yeah, not the most power efficient refrigerator. :P
Hi, I am seeing this video for the first time and I think the presentation is very good, I purchased the ADCBATT 12V 100ah Lifepo4 batteries a few years ago and yes they still work, but I was struck by this video and I was wondering, can these batteries be used in parallel with my original batteries? Thanks.
Crazy, I was just thinking about how to roughly approximate the size of my battery/solar needs and YT recommended this video. Incredible timing and exactly what I needed.
For the whole house requirements just look at your electric bill, it will tell you how many kilowatt hours you are being billed for and divide that by the number of days in the billing period.
Well done video and I really love the math you did to break it down to show us how it work. I make it simple as just saying you need a three to one ratio for your solar to your battery just like you did you had 600 W of solar and 200 amp hours of battery
I really like the use of a power meter as it gives you more realistic data for estimating your systems requirements. Make sure the meter you chose displays real power and accounts for the power used by the meter. Also, please adjust the battery’s capacity to less than 100% DOD, say maybe 80%, so the 100Ah would really be 80Ah. One last point is that in addition to Wh calculations an estimate of startup currents and VA for inductive loads is needed. These help in selecting an inverter and fusing. Thanks
I agree with your 80 percent capacity derating, Ive learned that some li iron batts also degrade if the they are topped off/maintained of over 80 percent of charge---thus a real usable capacity of 60%
@@rameye According to the AmpereTime website, these batteries have a built-in BMS. This management system should protect the cells from overcharging and overdischarging. This probably means that the full 100Ah is available and you shouldn't have to worry about changing the charging and discharging profile yourself. The one thing which is worth controlling in the charge and discharge rate - the gentler that is, the better. Lithium Iron Phosphate batteries are a lot more tolerant than the older Lithium Ion batteries which have higher capacity for given weight and volume - but for static energy storage weight and volume are less important. Additionally, the newer batteries don't contain (or contain much less) cobalt and nickel. AmpereTime suggest 4000 cycles and if you only charge once a day from your panels then 4000 equates to the best part of 11 years. By that stage you'll certainly have got your money's worth out of them.
Good video. A 100 watts an hour for a fridge is a huge draw though. I couldn't do that. My DC fridge will run over 5 days on 400 amp hrs of batteries with no power coming in at all, even using other appliances in the van, but sparingly.
Excellent video, very clear math! I would like to eventually have a system to power a window A/C unit or a split system, and then build out from there w/ additional battery capacity, and I have a similar plan set up for that as you described, so it's nice to affirm I'm on the right track w/ the equipment and the math. lol.
I loved this video, one of the best I have seen that explains how much battery do I need and how much solar I need to to be able to run my RV off grid.
I have a 12v fridge and it uses 100ah per night. With 600 watts of solar we’re fine on sunny days and even some rain. What kills the solar the most is shade. Time for the generator.
For those of us without solar panels is using a car's/truck's electrical system a viable way to charge a 1280 watt-hour battery quickly and efficiently enough to primarily use it with a DC charge controller and not for example using a 1200 watt pure sine wave inverter with a car battery as it's sole primary source to power it directly. The downside here being the alternator being 100 amps and the inverter not large enough wattage to take account for startup and peak wattage use.
Im in the market for a solar system as we speak and this information has been so helpful. Thank you for breaking it down. Now i know exactly what i need.
Impressive, the calculations apply to an rv? With cloudy and rainy days, factor in wind generation, what size is needed. Can you also use this set up to charge the lightening?
Well we just finished a home in Maui and we did 3,240 amp-hours at 48 V. Now that my friends is a big ass battery bank! The solar array was 40 kW and the inverter power output was a modest 24 kW and the generator was 60 kW. It runs a $10 million home flawlessly including the Tesla car charger on high. About $280,000 installed. And permitted.
Something you didn't cover in detail is how much solar and battery capacity you need if you need guaranteed power 24/7/365. In most cases solar has to be 5x and battery capacity 10x for this to be feasible so a ICE generator is required for interrupted power without having to spend 10x. A video covering typical worst case scenarios (i.e. a month long bout of clouds, rain, and snow) would be helpful and very interesting. Thanks for making these videos. They are well done and interesting. done and
I don't live too far from I live in the Illinois and Indiana border. June 30th we had a major storm roll through. I was that power until July 2nd. So have four days of no power. So I'm not doing this again I'm trying to build an emergency solar setup. Your video was quite helpful thank
Great video! Could you possibly share the link for that solar radiance info so we can look ours up? I tried a quick search, but didn't seem to find something basic. Thanks!
Thank you. Very helpful. Fulltime RVer. Looking to replace two one-year-old 91Ah AGM batteries in my RV. Have 1200watts of solar - wasted because not using lithium batteries.
I would at most use 80% of the rated battery capacity in the calculations of the needed number of batteries. Doing so to allow for the system to have enough capacity left at the end of life of the batteries (usually specified to be when they reach 80% of nominal capacity). It also lowers the DOD the batteries have to endure on a good day. Might even consider going lower than 80% as the battery isn't dead at the end of life (unless a cell goes bad at some time), but on the other hand wouldn't want to spend a fortune on a large battery bank that just sits there wall time ageing to death. (Especially if the regular power grid is still available as "backup" power)
Now *that* explanation of the math was great. I'm not a math wiz. Just another old widow. But I followed all that you explained. I am wanting to know which solar gen will keep my devices running if grid goes down. Your info is not what I need. I have ordered a kill a watt device to calculate my cell, laptop, desktop, tablet, router, electronic coffee pot ..not all at once! I am searching for a solar gen I can afford and panels for it that can keep me going. I live in an apartment and have a 10 lb dog. I have begun prepping $lowly a$ I do not work anymore. Katrina in N.O. and the Texas freeze, and Hurr Ian made me aware I needed some things. I am subscribed to several websites to learn what to buy and how to use them.
This is pretty helpful. Hoping you have a video up on understanding electrical diagrams to make our own electrical aystem function right and be safe. Or hopefully you have plans to make such a video in the Future
I just became a full time rv’er and I am building my first solar system and I needed this help so bad! I’m trying to figure out how many 100w panels and batteries I need to Run my tv laptop and lights I was so lost
INterresting indeed.I am looking to augment my bluetti EB3A adding a 12V 100ah that i can charge with my 195watt solar panel . i can use my EB3A as charge controller MPPT that could give it a 1200WH + 268WH = about 1468 Wh. In case of power shortage my computer could last several hours including wifi connection to advance my work before saving and shuting off. A simple system for now. But i will be bying the bluetti AC200L that will be a big boost . THanks for sharing your knowledge.
I'm just starting to learn about all this battery, inverter dc-ac, dc-dc, it's still confusing. Your video is a fantastic resource to come back to, thanks .
This is a very helpful video and I learned a lot. I've still got a couple questions for you though : a) is there a version of the kill-a-watt device that I could run in line of a 12V system on my small fishing boat ?? b) can you recommend a batt. charger for this Ampere Time 100 Ah battery ? c) is there any particular process I should consider when charging & storing batt. between uses and over winter months w/ no use ? (continually charge ? charge to full & disconnect ... check monthly or so ?? or some other way ?) I live in Louisiana so no extreme weather issues. Thank you for your generous consideration, Sincerely ....................
what about limiting draw from the battery to 50% of capacity? You should also consider charging current needs. LiFe04 don't care too much, they take what you give it. But many AGMs like 10% of AH rating, or 10 Amps.
Excellent video; thank you! I recently watched another video where a fella was trying to do the same thing, and it was painful. Yours, however, was clear, to the point, and it is obvious that you have a good handle on the concepts presented.
I’m from UK but his still works , we just get more of this ☔️! 😂 this is has been the best explanation of what (sorry about the pun ! 🙄) is required when working out watt hours for running appliances. I’m currently (oops there it is again 🙄) looking at wind turbine generation as a supportive measure , we get plenty of that here . Well done 👍🏻 at a pace slowly enough to absorb . Many of these are too fast . Good job , I’ve signed up .
Subscribed. That was very useful. Very clearly explained and not overly technical. I now feel that i understand how to figure out what battery capacity I need. Thank you very much.
Something that I have found is that it's one thing to calculate these figures in theory but the reality is sometimes a bit different. When you're charging your batteries from solar and via an MPPT charge controller, you might get full output while it's in bulk, but as the battery gets close to being full, it will usually go into absorbtion mode which slowly tapers off your output and if you're using a AGM, it will then go to float when it's nearly full. So this can mean it takes a bit longer than the calculations would estimate, to get a full charge.
It just amazes me that these wattage-measuring devices can tell you the hours since starting and the watts used since starting, but you have to pull out a calculator to figure out the average power used for that length of time. It would only take them a few lines of code to calculate kWh for you and also be able to have it display that in what we actually use - Watt-hours.
This was awesome information! 👌 I would like to know what the impact is if any of the efficiency of a solar panel in all those figures. Some quote as low as 19% etc
The explanation was great but I think you forgot about the amount of power to charge the batteries and the time it would take to charge the batteries. With 3 200W panels. How do calculate the Watt hours to charge the batteries and charge time?
Great explanation. Just the type of information I”Fe been looking for to build a solar backup system should we get a hurricane. Keep up the great work. I look forward to your upcoming videos.
very good info. I design and install off grid systems and have lived off grid for 20 years. firstly, living efficiently is the key and we use around 5.5Kw/day (Kw hours if you like). 3 - 3.5Kw is used per day just to run our fridge and chest freezer. so the most important part of design is to choose the most efficient refrigeration. most fridges give you a kw/year consumption rating, and this is great, but the rating is usually in ideal situations. if you have kids, who stand there with the door open and multiple trips to the fridge, the fridge will use way more power. Inverter fridges seem to be the best option. my old fridge is very inefficient, though 20 years old and was marketed at the time to off grid users as only using 1Kw/day. so you can see my fridge uses a lot more than the manufacturer stated. the rest of our load is electronics, lighting etc, all adds up to around 2Kw/day. No ac, no electric stove top, hot water etc. we have 1600Ah - 24V wet cell lead acid battery bank that is 20 years old, and probably only holding 50-60% of rated storage nowadays. but when new, at 50% doc (depth of cycle, we had roughly 20Kw of storage. so enough to keep us going for three days with no sun. 4rth day, kick on the generator. anyway, hope that all helps someone. cheers
I know this is outdated but thanks for contributing....my situation is quite similar and those real world examples should be very beneficial to anyone considering solar or alternative power, thanks
I am a retired electrical engineer, and I see a lot of misinformation surrounding solar systems on TH-cam with content providers mixing up power, energy, efficiency, and capacity. You did a great job here! This information is very helpful for people trying to size their systems. Thanks!
Thank you sir!
All I need is jumper cables and three nipple clamps to have a good time.
Well I'm in the solar industry and I can tell you you are 100% correct. I tell people to ask the sales person what the difference is between power and energy and if they can't rattle it off the top of their head then kick them out the front door. Then there are some guys that are so confident they talk about capacity of a battery bank in K dubs. It irritates the hell out of me! Or the newspaper talks about a huge generator installed and it makes 30 kW a year. 😂. I asked them if they have a water system that produces 60 psi per year. 😂
Yup. This guy is on point. There is another guy that is really good.
He is the Mr. Rogers of solar information.
Will Prowse, I believe
@johnmadsen37 Well I thought it was funny 😂
I'm amazed... Someone on the internet who actually knows the difference between power and energy. I started googling this stuff and found that more than half of the hits were people talking that clearly had no idea. Thanks, this was super helpful.
Thanks! Though I HAVE been repeatedly called-out for co-mingling the terms Watt-hours and Watts per hour. hahaha
My rule of thumb for anything you want to run pretty much off the grid indefinitely is to take your daily device power consumption for a 24-hour period and multiply it by 3 to 5 to give you several days of capacity in your battery bank in case of a string of cloudy days or snow-covered panels in the morning. This usually gives you a good base to carry through even a string of poor solar days. Then add enough solar panels to be able to charge your battery bank in 1 or 2 days from empty to full. This size of system will only use a fraction of the storage on a typical day with decent sun but will still have enough capacity that you don't need to babysit it all the time when the weather is bad.
I got a 300 ah Ampere Time with the last of my savings and a charge controller and inverter so I can have at least some power for a small window air conditioner after hurricanes and to save some on my electric bill since I`m on SSI disability and utilities may skyrocket cutting into my small check. I live in a 5th wheel camper so my bills probably won`t ever be too high but I just moved in. I have solar power stations for other things like a freezer, dlorm fridge, and smaller stuff.
This is good advice and i wonder why more people don't also run a windmill, there is heaps available, they work well and we use them at sea. However i assume it's noisy in suburbia but off-grid means remote, imo.
@@rasta77-x7o There are generally stronger winds 'at sea'. Rule-of-Thumb is an average of 13 mph wind is needed to justify a wind gen. And that's NOT common.
I bought a 500 watt WG dirt cheap; and my area does NOT a 13 mph ave. But when it does get windy I want to take advantage of it.
I'd shoot for enough panels to get a full charge in ONE DAY.
One other significant point. The more you oversize your batteries vs daily draw - the longer their life span will be. There's no free lunch with physics but equally investment up front and IF You can avoiding heavy loads (C rate) will pay you back.
I have four of those same batteries in my shop that has no power otherwise. 6 100 watt panels keep them up just fine considering I use the shop mainly on weekends to scrap cars and other metals. I can run a sawzall, 12 volt LED lights, a fan to circulate heat, chargers for cordless tools, and whatever else for the entire weekend. These batteries are exceptional for the price. I've never had any issues.
I am so glad I found this channel I live in the same area and I am just starting my journey into me of a self sustainable way to power my home. I didn’t follow all of the logic, but I will be returning to this video until I do. Thank you.
This was VERY helpful. The only suggestion for dummies like me is that you just round up from, say, 485 to 500, even if it's less accurate. The whole numbers make things easier by far! But yes, I watched this twice and hit rewind a few times, and it was much easier to follow than many videos on the topic. Thank you1
Thanks for the kind words! Making videos like this for TH-cam is often such a tight-rope walk...I know that if I over-simplify, I'll definitely get comments that I'm not being precise. So yeah...I try to walk that line and find that I'm rarely successful. hahaha Still, I'm glad you got some value out of it. :)
@@ReeWrayOutdoors also when it comes to powering critical equipment its best add margins onto theoretical values like capacity and power consumption.
This is the information that you NEED above all else! You NEED to know what your usage (rate of consumption) is over time. No other info is as important. You can now set up minimum and maximum usage over time and choose the capacity of storage that is needed! The Watt mater is the best tool in the arsenal. How are you supposed to know what you need, if you don't know what you consume? This is the area of solar power that people need to become educated in!
Use of the refrigerator as a reference, and project is brilliant! So many folks throw up random information which doesn't correlate to real world needs.
One of the best things you can do if you live totally off the grid is to use as many smaller 12v appliances as possible, so you only have to turn on the inverter in certain situations, saving quite a lot of power, and therefore money.
Easier to design and live around a system based on 48 Volts. More power, less copper, and when it comes time to run AC appliances, you won't have to play the power rationing game. You can add a 48 to 12 Volt converter to power your 12 volt buss. Electrical Food for Thought...
@@s.mendez7160hello I have a ecoflow I guess with that more solar panels rt to keep more charge comeing in
@@irenealvarado3494 You decrease the charge time with more panels, or said another way, you increase the charge current into your battery bank.
This is probably the best video on solar for non commissioned solar officers...please ..since you are so gifted..make some more...very real ..very simple..and i will call Ampere time for a very big order for my projects...simply because i believe you...
Great video. To me, it is all about using the AC, refrigerators, heaters and other high end energy consumption items. This will tell me how to set up my system.......Based on a little bit of luxury camping. Boondocking in the high heat or winter is why both AC and heaters are needed. Maybe having solar and and inverter generator would be a good back up. All this seems EXPENSIVE!
yeah, it's not cheap, for sure. But compared to even just 5 or 6 years ago, the prices have come down dramatically, if you can believe it.
Excellent explanation and detail without any background music!!! Keep up the great work!!!
And I was JUST thinking..."hmmmm, maybe I should start adding background music..." hahaha!
I like that he WASN'T "yelling" at the camera, or constantly changing camera angles, (for effect....) Those drive me to click off !!!!
I’ve got 700 watts of solar and two 30 amp charge controllers feeding a 200 ah Ampere Time Lifepo4 battery. That goes only to a 5,000 watt 12 volt inverter. It’s plugged into the shore power for the trailer which feeds 3-125 ah sealed lead acid battery’s . Should I use a generator or actually plug into shore power the cable is unplugged from my Solar inverter system. It’s fused and has breakers from the panels and to the lithium battery. I spent last winter in the Quartzite/Yuma area. The lithium battery worked flawlessly and I never had a single problem. Your calculated system requirements helped immensely with my purchases.
Wow ive watched so much on solar and batteries and always was confused, you made this so simple to understand i truely thank you soooo very much , simple math and explained perfectly....im working on a 17 foot camper and want to start gathering my electrical system components and you helped me tremendously.....thank you very much
Excellent video! I am a huge fan of solar and understand that you need to balance your expectations. My purpose for solar is backup power, and I determined first how many panels I could support, then purchased mostly 12v items, including a dc fridge that could be supported simultaneously by the panels, then purchased batteries that were 4 times the capacity of the load during a 24hr time period. This will give me 4 days of dc fridge, lights, fans, laptop and phone charges, and various small electronic recharges. And I have a Honda i2000 that I plan to top off the batteries daily and intermittently run ac appliances like microwave and toaster oven. If real world testing shows I have power to spare, I would like to add an inverter as well to lesson my dependance on the generator.
Great point about 4 days of power, you would hope to get some sun every 4 day cycle. I know the 24v fridges are bigger than the 12 v, I wonder if they’ll surpass 12v sales and popularity. Still considerably smaller than current mains supply fridges, but perhaps two would do the job? What is the capacity and price of your battery system please?
I like the Edison type batteries because you can run them down very low without damaging them, and on top of that you can maintain them and even refresh them later into new batteries by switching out the acid.
You can still get these types of batteries from China and Russia.
I plan on getting a big battery bank, solar panels, invertor and backing it up with a couple small Honda propane fired generators and a very big propane in ground tank.
I want a 12,500 gallon tank so I could go 10 years if I need to on the 10k of propane in it.
If we get set back to the stone age, I want to be good for 10 years even if I do nothing else for supplies outside my property.
@@jasonbourne1596 when does propane go on sale?
Generators can be run on hydrogen.
10yrs food supply could take up a bit of space. Secure, and environmentally controlled storage.
Need to think of intruders/invaders. , , could be a sizeable meteor, that intrudes...lol
Have fun 🎯😎☕
Probably better off with multiple smaller tanks, one serious leak could ruin your decade.
That is one of the easiest explained breakdowns of such a relative and common query, that I am agasp! Thank you kind sir for the time taken to do that for folk like me.. yur neighbors in , IN!
For offgrid use i use a 9cf 24v refrigerator and a 10cf 24v freezer. Using 3 200watt panels, the system works great using 4 100ah agm batteries. With enough reserve to go a couple of days of fog. Great video.
What size inverter do you use?
But with agm is you want your batteries to last then you should only take them down to 50% depth of discharge which is 12v. So realistically you only have 200ah
Can i ask for the brands of the fridge & freezer, please? Would like to get a set like that for myself.
@@j5892000 both refrigerators use about 15 amps, when running at the same time. They don't run continuously.
@@dirtydog288 with the refrigerators i don't use an inverter. They're 12v.
I do use a 1000w inverter to run lights at night and a computer during the day.
I went off grid ten years ago and built my own home single-handedly. In June 2021 I bought a Tesla model 3 and wanted to charge it using the sun. Here is my setup: I have three 300 watt panels. I have a flat roof and leave them flat as I live in the middle of Oregon. (If I tried to point them south I would only get rays between 11am and 2 pm.) On a sunny day I get almost 800 watts. I feed this energy into a 60 amp MPPT charge controller keeping six 100 amp hour Battle Borne batteries charged. The key is using a 3500 watt inverter (pure sine wave). On a sunny day my Tesla wants 1500 watts if I set it to 12 amps and get 6 miles of range. On a cloudy day I need 1000 watts so I change the Tesla charging down to 8 amps and get 4 miles of range. I use thick wires so I do not loose current and protect batteries and inverter with 300 amp and 200 amp circuit breakers. If I tried to use 12 amps it would drain the batteries real quick so I keep it at 10 or 8 amps and it charges for 14 hours a day. This actually is as good as if not better than someone on the grid using 120 volts AC. Make sure you use a bonding plug (connect neutral to ground) if Tesla won't charge. Some inverters don't need one.
Exceptional video! Each calculation was explained very clearly. Whenever folks start to contemplate their needs in terms of solar panels, solar charging capacity, battery size, system voltage, inverter sizing and losses, as well as distribution (110 vs 220), it tends to be very surprising. As you have spelled out in this video, it takes quite a bit of equipment and expense just to power a residential refrigerator off of solar and batteries. When you throw in those extended periods of poor solar conditions, and the equations for how many more panels and batteries are needed to account for that, it becomes clear that staying grid-tied, if you can, makes a TON of sense. Thank you for doing such an excellent job with these videos...they are far better than most!
It depends on your local cost of electricity, but solar usually pays for itself. Home battery backup doesn’t unless to have loads that you want to ensure never get interrupted. Here in California with our cost of power and the issue of taking power delivery out of service during high winds was enough for me to get a Power Wall. I have an automated system that keeps all my critical loads powered whether I am her or not.
@@matthewhuszarik4173 How long do you think it would take for this $2000 system(2 batteries/3 200w panels) to pay for itself just powering a fridge?
@@sjagain I would guess longer than the batteries will last.
Everyone else I’ve watched says you need about 3 times the amount of watts used per day. To cover for the days of no sun. So, suddenly we are talking $6k worth of batteries. You not charging those with 600w of panels.
I have been running numbers, I need something like 65k worth of batteries alone to go “off grid”.
We use about 60kwh per day 🥺
@@MrTruck1012 Well since these are LiFePO4 batteries they should easily achieve 15 to possibly 20 years of service before calendar aging completely takes them out. They will likely never see the number of cycles to kill them in solar duty before they fail due to age. The main thing you have to decide is how much you really want to run since a system that is being used to keep the fridge and or freezer on all the time could also power all or most of the lighting circuits in a modern house that uses LEDs along with a couple outlets without adding much more if any additional capacity and would really come in handy when the power is out. The batteries are expensive but there are ways to get by cheaper if a person wanted to DIY a system with raw cells and a BMS or 2. Used solar panels are sometimes sold dirt cheap. I bought 24 used 345watt panels for my system for ~$3800 that were only installed for 9 months and were about 1 year from Date of Manufacture. I paid $150 per panel plus tax. So if you look you can often find deals on craigslist and facebook marketplace on panels.
Going off grid won't be as inexpensive as being on the grid, especially if you buy a fancy new system with all the bells and whistles and have it professionally installed but if you start small with the goal of just keeping a fridge and freezer on plus a few lights and maybe a couple outlets you can often put a decent dent in the electric bill while also providing you with a bit of backup power when the grid is down.
I power my entire house except the range and internet equipment from a single 6000 watt split phase inverter that cost me $1200 about 2 years ago, Along with 3 X 60A MPPT charge controllers costing a total of $435, a ~375Ah 16S 48V LiFePO4 battery bank built from raw cells Measured capacity is a bit over 19.5KWh for ~$4500 with 3 BMS units included (I could do this slightly cheaper now). Water heater conversion to 48V (~$220) in parts and wire. 24 solar panels for $3800 plus about $200 in fuel to go get them. Ground mount solar array using heavy duty galvanized unistrut $1300. Various wire and cable along with fuses, breakers, busbars, shunts and conduit ~$2600. All totaled that comes to a bit under $14,300 not counting my time but it is a hobby after all.
In the past 2 years I have been almost completely off grid except for the electric range and my fiber internet CPE, router, and 2 access points. So I have already saved a bit over $2100 off my electric bill. While I don't expect to get much over 15 years total out of the battery bank, it could happen. I expect the system will pay for itself in another 12 years or so, maybe less considering how much electricity has gone up in the area. At that time I will need to buy more batteries and possibly a new inverter or charge controller. The biggest benefit so far has been that in the last 2 years we have had 3 local power outages, all from bad storms 2 times were only out for a few hours but one of the 3 the power was not restored for nearly 3 whole days and during that time I didn't even notice except the internet and cell service throughout the area was down.
This was a great video. Simple and detailed all at the same time. I'm sending to my dad for him to learn too! I think he'll follow you just fine!
I'm glad I found your video. The way you explain how solar works and what you need to make it work helps me to understand it all better. I'm sure I'll have more questions at a later date.
I can attest the customer support ... and there were some minor concerns and all was resolved quickly and with good information.
I know this is an older video but youve just made an entire video on something i keep bringing up to myself in a quest for a small DIY solar setup ive been building. Of course you need battery capacity to run something while there is no sun...but you ALSO need enough solar generation to run said item while there is sun AND have enough surplus to bring your battery back up to a 100% SOC at the same time. You are the first person ive seen to actually bring up this real world way of having solar. I didnt find this out until well after building my system. Had i known before hand, i likely wouldnt have spent money on 12V only inverter and would have well upgraded my charge controller as well. At this point im doing all i can to make things work with the several hundred dollars i have invested into a system that is almost maxed out.
One more addition needed here and it's the idle current draw of the inverter. Normally when the fridge is running it cycles between on and off, and the off state draws almost zero power. Your inverter standby power will still be drawn during this time and this can add up to a large amount of watt hours quickly even though there is no load.
Absolutely correct! 💯 I was thinking that my rounding things up would have mostly offset that, but it's a real thing and probably should've part of that walk-thru. So thanks for mentioning that.
A lot of people scale too low or they talk about whole house systems and never define the proper total capacity. Your example was simple, explained well, and scalable.
Great video. Something that got my attention a few years ago was when I plugged a Skill 7 1/4 inch worm drive circular saw into a 2 kilowatt gas generator. The saw draws 15 amps at 120. Volts or about 1800 watts. Should work. What I forgot was the extra energy needed when I pulled the trigger. Yup killed the gas generator. (I've been using the Kill-a-watt units for years, great product.)
It's not just the running power.
Thankyou thankyou
Was so excited when you chose full size fridge for example
Took me a couple days to figure this out all on my own starting from zero knowledge of solar. This video would have helped big time a few days ago lol.Very clear and concise. In TX, in these past 90 days of 100+ weather the AC makes my daily usage 75,000 watts...Im gonna need a ton of batteries lol.
During the day you will be pulling straight from the solar panels and not the batteries! Batteries are for when the sun isn’t shinning(nighttime) or when your pulling lots of power beyond what the panels can do
@@thomascranor9505 During the day my ac plus other utilities hover at around 5,000 watts/hour, how many solar panels would I need to keep that going from noon to 6 pm? What about rainy days and cloudy days? Also I don't want to backfeed the grid ever so that's why I want to stay on battery use and storage only.
Thankyou for sharing. What power invertrr do you reccomend to back up a reguar size houshold refridgrrator?
Enjoyed the lesson, thanks! Your example is very practical too; keeping a refrigerator running is probably the most critical need in a long term power outage situation. One positive fact which significantly prolongs the battery’s watt hours, is that a refrigerator does not need to be powered 24/7 to do it’s job. During long outages here in eastern NC, to save fuel, we will run our generators 3-4 times a day for 3-4 hours.
Same here in TX
@@SomeBuddy777 another power saver....I'm from Florida but now live in South Louisiana. Between me and the in laws we use a bunch of deep freezers for fish and game. Freeze clean 2ltr bottles of water and keep a few in freezers and fridges. It helps reduce cycling. We do it year round. In the event potable water is in short supply you can thaw them out.
I purchased two, 200ah Ampere time batteries, and I Love Them. We are on day 9, without plugging in, With 420w of solar. Best investment we made. I may build a few power boxes with their batteries at a later date.
Very nice and clear video. Unfortunately, at 7:50 you are completely messing up the units. The only unit that is sort of correct in this equation is 'h' for the duration of the test. The usage is not 6201W. It is 6201Wh, which you then divide by 38h (lower case h!) to yield 91.2W. *Not* Wh!
The unit W is short for Joule/second, where Joule(J) is a measure of energy expended. So energy use is measured in Watt multiplied by a time unit such as hours.
If anything, the outcome you are trying to get to is 91.2Wh/h, also known as 91.2W
It bothered me a lot to see this unit mess and was pleased to see that somebody actualy pointed it out thoroughly in the comments. It seems to me that so many people just can't get their head around the difference between units of amounts (how much) and tempo's (how fast).
I’m literally fresh to all this but living on a boat where it’s essential to know,
Thank goodness I found your channel
Thank you so much
It’s a good idea to make all your calculations based upon winter performance when the number of daylight hours are lower and the sun is lower in the sky. If you can, use solar trackers to maximise the output of each solar panel. On my journey with playing around with solar, I ended up dehydrating lots of food for a food storage solution so I am not dependent on my fridge freezer if I can’t generate enough energy from solar. I grow my own vegetables as well so when it comes to dehydrating veg, it’s useful that there is still plenty of sun at harvest time to use my dehydrator.
Everyone should go on this journey to appreciate the power consumption of various equipment. For me it changed my mindset when purchasing new electrical devices. I usually look out for power ratings before I look at the features of the product, and whether I can power the device directly from DC.
I also try to make sure if I can power any device directly from DC, I’ll power it from DC. A mistake I see in a lot of You Tube videos are people powering or charging DC devices (5v, 12v, 18v) using AC to DC adapters. They don’t seem to understand energy losses in converting DC to AC and then back to DC. In my eyes, it’s bad practice.
Excellent insights. Thanks for contributing to the conversation!
Hi. I would agree that it seems pointless inverting up to AC to convert back into DC for many of our devices. Have you considered whether the loss in the inverters is more or less than cable losses? For example, I imagine running 12v the length of your house to power LED lighting would have quite high voltage drop unless using fairly heavy cables. It may be worth taking the hit converting it to 240AC so you don't lose as much in the cables. I suppose 110V in America would be slightly less beneficial due to the lower voltage but just wondering if you had worked it out as its something Ive always wondered about?
@@davidleisk580 I helped a friend wire a DC circuit around an old derelict house in the middle of nowhere powered by Solar. Plenty of sunshine and plenty of land. We rigged it so there was a main battery bank (48v) charged by the solar panels. Depending on the requirements around the house, we stationed various secondary battery banks around the house for various purposes, some battery banks were 36v, some were 24v, some were 12v. They were all automatically charged/topped up by the 48v main battery bank. They all had isolator switches. Upstairs lighting was on one circuit, downstairs lighting on a separate circuit, ‘workshop’ had a separate circuit to charge the cordless tool batteries etc.
We didn’t bother calculating efficiencies into wiring decisions, we just designed a solution which we thought was practical. There were numerous reasons why we decided to have secondary battery banks around the house, one was simply to increase energy storage capacity. When the sun is out, it doesn’t take long for the main battery bank to become fully charged, meaning you are losing energy which can be stored. It makes sense to use the main battery bank to charge all the secondary battery banks so you can take advantage of sunny days.
Another advantage of having secondary battery banks is that each station is independent. If the main battery bank disconnects because it’s reached a low voltage threshold because let’s say the workshop has drained it you still have energy stored in your kitchen, lighting and living room secondary battery banks i.e. the lights don’t go out even if the main battery bank is disconnected.
In summary 48v main battery bank wired to each secondary battery bank. Each secondary battery bank has isolator switch plus a solar charger/regulator to auto top up from 48v main battery bank.
Don’t know if that answers your question in a round about way.
@@davidleisk580 The 5-15% efficiency loss in the inverters, depending on which brand you have, is almost always far more of a loss than the voltage drop found in the great majority of cable setups, even those running the length of a house.
On my sailboat, this year I replaced two - 4D AGM batteries with two 12v x200amp Ampere Time Lipo batteries. Before the final install I couldn't get the batteries charged up to capacity. I contacted support through email. They were prompt with a response. I was just impatient and just needed to let the batteries charge longer. So far everything has been fine and haven't had any issues. The weight savings is unreal! Those 4D's are hernias waiting to happen.
The way I understand charging batteries is the speed of charging is related to the difference in voltage between the battery and the charger. So when getting close to full it just takes longer.
The battery's ability to charge is another important constraint. Ampere Time specs a MAX charge rate of 100A, but if you want to get the full life out of the battery, you should use more like 20-50A. If other decisions drive you to a 3 kW solar array, for example, then you should realize that a pair of these batteries will only handle 12.8V x 100A x 2 = 2.56 kW at 100A, or half that if you want to prolong battery life. We sized our system to cancel out our utility bill, for example, and then got the minimum battery capacity needed to charge under full-sun.
ty!
Very good explanation,the guys who supplied my 2400 unit . The installers did not actually know how to connect, despite having a circuit diagram. I had to show them
This is extremely helpful! Easy to understand and well presented with a focused message. I'm planning to set up offgrid power to my machine shed and want to run lights and maybe an outlet to recharge tool batteries. But now I can likely calculate what I would need to run a corded saw. And I'm surprised at the price of that battery. Two years ago I converted a cargo van to be a camper and used one $300 96amp hour glass matt battery. Lithium batteries were $1000 at the time. I really should upgrade to LiFePo. Thanks for your post!
love ampere time batteries I have five that I use for several dif setups also Eco Worthy batteries have been good for me as well completely satisfied with mine
Yes... useful data/info indeed, as I'm currently trying to sort out what I need for a solid back-up system. Thanks and Thumbs Up !
Great job. Thank you for sharing. Now let's look at the 10 year de-rating curve for the battery to include that 20% reduction and reduction of solar panels (-20%) efficiency add 50% more battery capacity for beyond 10 plus year coverage on your battery requirements. De-rate curves need to be included so end of life for that system is extended. Peace and blessings to all. ❤❤❤
It;s a decent battery. Just don't let it freeze--no low temp protection. That said, I made a 600 AH system with their 200 AH batteries and a 4000 watt inverter. Works AWESOME! Best part is it's not a sponsored 20k battleborn/victron everything build.
I think you can add battery warmers to it though utilizing the inverter/charger right?
@@alexkennedy5133 You can. But I installed them in behind my 5'th wheel's kitchen cabinets directly under the bathroom. It's a heated otherwise unused dead space that houses the furnace and water heater, and therefore stays warm all year.
I've looked at solar several times over the past few years, a
nd by "looked" I mean: I looked at a few websites and videos and got frustrated and quit looking... After viewing this video, I really feel like this is very doable. You did a great job, my friend!
On the refrigerator example some Modern refrigerators have a heating element that operates during a defrost cycle and that can raise the refrigerator power consumption to over 700 Watts for a period of time. That should be calculated into these measurements.
For sure. That's another reason to measure the power consumption over a period of days rather than just a few hours.
Your video is very useful and you explained very well. I would like that you consider a video adding a fuse to the battery and any fuse you may consider necessary. You have the ability and the skills. Your video is A+
First off--excellent video! If you will be using a Kill-a-Watt to calculate your avg requirement you'll need to multiply it by factor 1.2 (min) because the 485 watt avg daily solar for your panel is based on current at the panel itself, before being conditioned and stepped down to charge your batteries and/or be inverted back to AC for your appliance load. So each 92 watts through the outlet requires at least 110 watts of solar production at the solar panel leads. Conversely, 12/24v chest freezer (which can be used as a fridge, too) is really the best way to do this "indefinitely" . You will only need a small charge controller, one 250w panel and one 100ah 24v battery. The daily consumption of a 12/24v 9cu' freezer is less than .75Kw, and less if it's in your midwest basement at 65F*ambient. You'll use about 500watts of your 2500watt battery capacity (DOD--20%) daily, so it's ok to go with an AGM in this particular case, and still have enough storage for a three -day total eclipse! 😃 Plus they have very thick insulation(4-5" walls) and will stay cold for at least two days after total loss of power.
We have 2 separate systems. The first is 200 watts of solar panels, 1200 watt inverter, 200 Amp charge controller with about 450aH battery storage.
The second system is 9- 15 watt panels, a 400 watt inverter, and a 400 watt charge controller with 105aH battery.
Also a 20 watt panel, 45 watt charge controller, 150 watt inverter with about 2-35aH batteries for charge-way radios and phones.
Great video, thanks!
The only one small mistake I see (maybe somebody already mentioned that) is that wattmeter detects only refrigerator working time, but sometimes it in idle mode. You need to calculate the time by your own and then calculate an average consumption based on that time. So you don't need so big battery to support it.
Thanks for the kind words! But thinking maybe you skipped some parts? I actually explain that in detail starting @6:30 so the 100W per hour that I'm using is rounded up from 91W per hour - which is the calculated average consumption my refrigerator uses (from the total of 6201W over 68hrs sample period). Yeah, not the most power efficient refrigerator. :P
Hi, I am seeing this video for the first time and I think the presentation is very good, I purchased the ADCBATT 12V 100ah Lifepo4 batteries a few years ago and yes they still work, but I was struck by this video and I was wondering, can these batteries be used in parallel with my original batteries? Thanks.
Great explanation and presentation. 👌
Crazy, I was just thinking about how to roughly approximate the size of my battery/solar needs and YT recommended this video. Incredible timing and exactly what I needed.
For the whole house requirements just look at your electric bill, it will tell you how many kilowatt hours you are being billed for and divide that by the number of days in the billing period.
This was extremely well done. Very brief, clear and helpful.
Enough said.
Much appreciated!
Brief? Brief would be at least 60% shorter without all the advertisement for the battery
Well done video and I really love the math you did to break it down to show us how it work.
I make it simple as just saying you need a three to one ratio for your solar to your battery just like you did
you had 600 W of solar and 200 amp hours of battery
I really like the use of a power meter as it gives you more realistic data for estimating your systems requirements. Make sure the meter you chose displays real power and accounts for the power used by the meter. Also, please adjust the battery’s capacity to less than 100% DOD, say maybe 80%, so the 100Ah would really be 80Ah. One last point is that in addition to Wh calculations an estimate of startup currents and VA for inductive loads is needed. These help in selecting an inverter and fusing. Thanks
I agree with your 80 percent capacity derating, Ive learned that some li iron batts also degrade if the they are topped off/maintained of over 80 percent of charge---thus a real usable capacity of 60%
@@rameye According to the AmpereTime website, these batteries have a built-in BMS. This management system should protect the cells from overcharging and overdischarging. This probably means that the full 100Ah is available and you shouldn't have to worry about changing the charging and discharging profile yourself. The one thing which is worth controlling in the charge and discharge rate - the gentler that is, the better. Lithium Iron Phosphate batteries are a lot more tolerant than the older Lithium Ion batteries which have higher capacity for given weight and volume - but for static energy storage weight and volume are less important. Additionally, the newer batteries don't contain (or contain much less) cobalt and nickel.
AmpereTime suggest 4000 cycles and if you only charge once a day from your panels then 4000 equates to the best part of 11 years. By that stage you'll certainly have got your money's worth out of them.
@@mb-3faze thank u for the additional info
Good video. A 100 watts an hour for a fridge is a huge draw though. I couldn't do that. My DC fridge will run over 5 days on 400 amp hrs of batteries with no power coming in at all, even using other appliances in the van, but sparingly.
Excellent video, very clear math! I would like to eventually have a system to power a window A/C unit or a split system, and then build out from there w/ additional battery capacity, and I have a similar plan set up for that as you described, so it's nice to affirm I'm on the right track w/ the equipment and the math. lol.
Look at EG4. They have a mini split unit that can accept solar power directly.
I live in south Texas. Sun 20yrs a day 🤣🤣🤣just curious why you didn’t just round off to 3 full days?
I loved this video, one of the best I have seen that explains how much battery do I need and how much solar I need to to be able to run my RV off grid.
Easy to understand like no music now I can actually use the info you show kudos
I have a 12v fridge and it uses 100ah per night. With 600 watts of solar we’re fine on sunny days and even some rain. What kills the solar the most is shade. Time for the generator.
I have some education in electronics and find your presentation to be on point . Thank you very much for sharing your knowledge.
Was glad to learn that it does have an internal BMS.
For those of us without solar panels is using a car's/truck's electrical system a viable way to charge a 1280 watt-hour battery quickly and efficiently enough to primarily use it with a DC charge controller and not for example using a 1200 watt pure sine wave inverter with a car battery as it's sole primary source to power it directly. The downside here being the alternator being 100 amps and the inverter not large enough wattage to take account for startup and peak wattage use.
Im in the market for a solar system as we speak and this information has been so helpful. Thank you for breaking it down. Now i know exactly what i need.
I've watched others talk about solar and batteries M but your presentation was clear and easy to follow, Thanks 😊
Awesome, thank you!
So how much money did that cost you to run the refrigerator with the batteries in the solar versus running it off your house AC?
Impressive, the calculations apply to an rv? With cloudy and rainy days, factor in wind generation, what size is needed.
Can you also use this set up to charge the lightening?
Well we just finished a home in Maui and we did 3,240 amp-hours at 48 V. Now that my friends is a big ass battery bank! The solar array was 40 kW and the inverter power output was a modest 24 kW and the generator was 60 kW. It runs a $10 million home flawlessly including the Tesla car charger on high. About $280,000 installed. And permitted.
Something you didn't cover in detail is how much solar and battery capacity you need if you need guaranteed power 24/7/365. In most cases solar has to be 5x and battery capacity 10x for this to be feasible so a ICE generator is required for interrupted power without having to spend 10x.
A video covering typical worst case scenarios (i.e. a month long bout of clouds, rain, and snow) would be helpful and very interesting.
Thanks for making these videos. They are well done and interesting. done and
Thanks.. Love your clear teaching style and excellent dictation voice.. passing you along to others..
I don't live too far from I live in the Illinois and Indiana border. June 30th we had a major storm roll through. I was that power until July 2nd. So have four days of no power. So I'm not doing this again I'm trying to build an emergency solar setup. Your video was quite helpful thank
Great video! Could you possibly share the link for that solar radiance info so we can look ours up? I tried a quick search, but didn't seem to find something basic. Thanks!
Thank you. Very helpful. Fulltime RVer. Looking to replace two one-year-old 91Ah AGM batteries in my RV. Have 1200watts of solar - wasted because not using lithium batteries.
I would at most use 80% of the rated battery capacity in the calculations of the needed number of batteries.
Doing so to allow for the system to have enough capacity left at the end of life of the batteries (usually specified to be when they reach 80% of nominal capacity).
It also lowers the DOD the batteries have to endure on a good day.
Might even consider going lower than 80% as the battery isn't dead at the end of life (unless a cell goes bad at some time), but on the other hand wouldn't want to spend a fortune on a large battery bank that just sits there wall time ageing to death.
(Especially if the regular power grid is still available as "backup" power)
Now *that* explanation of the math was great. I'm not a math wiz. Just another old widow. But I followed all that you explained. I am wanting to know which solar gen will keep my devices running if grid goes down. Your info is not what I need. I have ordered a kill a watt device to calculate my cell, laptop, desktop, tablet, router, electronic coffee pot ..not all at once!
I am searching for a solar gen I can afford and panels for it that can keep me going. I live in an apartment and have a 10 lb dog.
I have begun prepping $lowly a$ I do not work anymore. Katrina in N.O. and the Texas freeze, and Hurr Ian made me aware I needed some things. I am subscribed to several websites to learn what to buy and how to use them.
This is pretty helpful. Hoping you have a video up on understanding electrical diagrams to make our own electrical aystem function right and be safe. Or hopefully you have plans to make such a video in the Future
I have lot to say.but I will make it in few words.
You the best on this video.and thank you for straight to the point info with fine detail.
I just became a full time rv’er and I am building my first solar system and I needed this help so bad! I’m trying to figure out how many 100w panels and batteries I need to
Run my tv laptop and lights
I was so lost
Excellent information. Straight forward, easy to understand and no marketing BS. Many thanks and a pleasure to subscribe.
Sir… you are a god send… that started to help me out understand how this works…
INterresting indeed.I am looking to augment my bluetti EB3A adding a 12V 100ah that i can charge with my 195watt solar panel . i can use my EB3A as charge controller MPPT that could give it a 1200WH + 268WH = about 1468 Wh. In case of power shortage my computer could last several hours including wifi connection to advance my work before saving and shuting off. A simple system for now. But i will be bying the bluetti AC200L that will be a big boost . THanks for sharing your knowledge.
I'm just starting to learn about all this battery, inverter dc-ac, dc-dc, it's still confusing. Your video is a fantastic resource to come back to, thanks .
Glad it was helpful!
This is a very helpful video and I learned a lot. I've still got a couple questions for you though :
a) is there a version of the kill-a-watt device that I could run in line of a 12V system on my small fishing boat ??
b) can you recommend a batt. charger for this Ampere Time 100 Ah battery ?
c) is there any particular process I should consider when charging & storing batt. between uses and over winter months w/ no use ? (continually charge ? charge to full & disconnect ... check monthly or so ?? or some other way ?)
I live in Louisiana so no extreme weather issues.
Thank you for your generous consideration,
Sincerely ....................
Great info very helpful. I’m totally into the small solar systems for my shed and such. Your info was very helpful in making my system better
Clear video and you've clearly shown the calculations on the screen. Good job and helpful.
what about limiting draw from the battery to 50% of capacity?
You should also consider charging current needs.
LiFe04 don't care too much, they take what you give it.
But many AGMs like 10% of AH rating, or 10 Amps.
Excellent video; thank you! I recently watched another video where a fella was trying to do the same thing, and it was painful. Yours, however, was clear, to the point, and it is obvious that you have a good handle on the concepts presented.
Thanks for the kind words!
I live in Columbus Ohio and I’m just starting to figure all this out. Great video Sir.
I’m from UK but his still works , we just get more of this ☔️! 😂 this is has been the best explanation of what (sorry about the pun ! 🙄) is required when working out watt hours for running appliances. I’m currently (oops there it is again 🙄) looking at wind turbine generation as a supportive measure , we get plenty of that here . Well done 👍🏻 at a pace slowly enough to absorb . Many of these are too fast . Good job , I’ve signed up .
Glad it helped!
Have you built a larger system? 4000w. Would love to see a DIY system. I halve how clear you are with your instructions. Thank you for your time sir!
I've done a video on a 24V 3000W system. And very soon, should have a video out on a 48V 5000W system. :) Stay tuned!
I’ve got to give it to ampere time there support is really great ❕❗️❕❗️👍🏼
such a practical video... I am new to solar and found this very useful! THANK YOU!!
Subscribed. That was very useful. Very clearly explained and not overly technical. I now feel that i understand how to figure out what battery capacity I need. Thank you very much.
Something that I have found is that it's one thing to calculate these figures in theory but the reality is sometimes a bit different.
When you're charging your batteries from solar and via an MPPT charge controller, you might get full output while it's in bulk, but as the battery gets close to being full, it will usually go into absorbtion mode which slowly tapers off your output and if you're using a AGM, it will then go to float when it's nearly full. So this can mean it takes a bit longer than the calculations would estimate, to get a full charge.
It just amazes me that these wattage-measuring devices can tell you the hours since starting and the watts used since starting, but you have to pull out a calculator to figure out the average power used for that length of time. It would only take them a few lines of code to calculate kWh for you and also be able to have it display that in what we actually use - Watt-hours.
You're right! haha and I'd gladly pay the extra few bucks for that. :P
This was awesome information! 👌 I would like to know what the impact is if any of the efficiency of a solar panel in all those figures. Some quote as low as 19% etc
For the uninitiated, (me) this is a very helpful overview. thank you
The explanation was great but I think you forgot about the amount of power to charge the batteries and the time it would take to charge the batteries. With 3 200W panels.
How do calculate the Watt hours to charge the batteries and charge time?
Great explanation. Just the type of information I”Fe been looking for to build a solar backup system should we get a hurricane. Keep up the great work. I look forward to your upcoming videos.
very good info. I design and install off grid systems and have lived off grid for 20 years.
firstly, living efficiently is the key and we use around 5.5Kw/day (Kw hours if you like). 3 - 3.5Kw is used per day just to run our fridge and chest freezer. so the most important part of design is to choose the most efficient refrigeration. most fridges give you a kw/year consumption rating, and this is great, but the rating is usually in ideal situations. if you have kids, who stand there with the door open and multiple trips to the fridge, the fridge will use way more power. Inverter fridges seem to be the best option. my old fridge is very inefficient, though 20 years old and was marketed at the time to off grid users as only using 1Kw/day. so you can see my fridge uses a lot more than the manufacturer stated.
the rest of our load is electronics, lighting etc, all adds up to around 2Kw/day. No ac, no electric stove top, hot water etc.
we have 1600Ah - 24V wet cell lead acid battery bank that is 20 years old, and probably only holding 50-60% of rated storage nowadays. but when new, at 50% doc (depth of cycle, we had roughly 20Kw of storage. so enough to keep us going for three days with no sun. 4rth day, kick on the generator.
anyway, hope that all helps someone.
cheers
I know this is outdated but thanks for contributing....my situation is quite similar and those real world examples should be very beneficial to anyone considering solar or alternative power, thanks
Was lloking at the Kill-A-Watt today. The generic is almost half the cost. Ordered it. Thanks.
Very helpful, well done so even I can under stand it. Did not know everything about the plug-in watt meter. Great little tool. Thanks
Excellent …. Just excellent … a thinking through of an oft ignored problem when sizing a system. Thank you ! Deserved a subscribe!