You have just enlightened me M8. I had seen the term blocking diode and bypass diode and assumed the two were the same. Thank you. I have been messing with off grid power for ~10 years and you just set me strait.
That is a really nice way to describe how things work. I already knew the basis but still really enjoyed watching your video. Totally agree that in your scenario you’re unlikely to require a diode. I wonder if I might though, as I’ll be building a solar fence where at times many panels won’t be in the sunlight so maybe that would yield different results. I’ll certainly film a test against that and see if it also works just fine without diodes. I’ll then also compare the diodes with Tigo optimisers as I haven’t really seen such a test but I think they go hand in hand when you look at how those optimisers work. Thanks for another good video!
Good video, very well explained re solar panels wired in series, but what about those wired in parallel? I have 3 panels (1x100W, plus 2x 160W) charging 12V AGM batteries for shed power. The 100W faces SSE, and both 160W panels face due South. One of the 160W panels is shaded each morning by a neighbours tree. Should I install a MC4 type blocking diode in the positive cable of each panel output?
You are right, in my first built east west 5KW unit I measured zero current running in the shaded part when the sun still was bright at the west side. Diodes produce losses, 0.7V siliciums
I would add only that a solar panel acts as diode ONLY in that when power is pushed to the panel it becomes an LED (light emitting diode), however the light emitted is not in the visible spectrum. Thanks for giving me some good laughs when you responded to people's comments though. Although I have a feeling those types of comments will never stop, lol. Great video, cheers. 😎
I have a question sir. I have all in one off Grid solar inverter which supports 3.5 KW panels. So there are 3 strings os 3 panels each that make up 3.5Kw. all 3 strings are parallel. Will it Be a problem If I place 2 strings iñ south direction and 1 string in West direction? Your reply will be appreciated. The reason for this is to get some power and try to keep the batteries topped up untill the sun goes down. Thanks
That depends on how many solar inputs the inverter has. If it has only one solar input, I would not recommend mixing strings which point in different directions.
What blocking diode would you recommend for a 100watt 12 panel. I have shade problems currently and panels in different locations. A part number would be great. Great video.
It does not turn off the charge controller, there is no switch or relay. When the battery gets full and the charge controller reduces power it just drives the panels away from the maximum power point, into an inefficient area of the solar panel curve so to speak. It will not disconnect the panels though.
@@OffGridGarageAustralia thanks for the answer and for the time you spend to give us free learning content. You, Will Prowse, David Poz and Jehu Garcia are the best solar teacher in the globe!
I have 4 panels 2x2 in series and both strings in paralel on both sides of my balcony. In the morning the sun is from one side than after 12 o clock fron the other. ON EACH SERIES strin one panel stoped working and I am wondering why. I do not haveb a blocking diode
Very good experiment and explanation. That confirms what i had thought regarding diodes and back current. Earlier today, i found som facts about solar cell tecnique, and read that a solar cell is a type of diode. But the current created by sunlight flows in back- direction of the diode/solarcell. That should explain why the solarcell does not block ” back-current” Back current in the way we ar speaking about will flow in forward direction thru the diode/solarcell.
I'm sorry if I'm a newbie, but the way i understood is, blocking diode and bypass diode is the same, it's just the way it is connected that makes it a bypass or blocking. if its connected in parallel in between the + and - in a pv array then it acts as a bypass diode. if it's connected only in the + of the PV in a one way strean of power flow then it wll act as a blocking diode. am i correct? please respond.
Physically, they are the same diodes, that is correct. Yes, you're correct. Bypass diodes are across the single strings in a panel to prevent total power loss during shading, while blocking diodes protect the panels from current flowing backwards.
that may be true but show us a situation where one panel would be it total darkness while the other is in lighted area. even in shaded area the solar panel is still producing
Hey Andy I need some help with bypass diodes I was given some panels and one of them the center bypass diode was accidentally broken off any ideas how to find out what one I would need to replace it with I’m talking about the one on the back of the panel in the center junction box the whole box is gone but the terminal tabs are intact
So here is my question. If I have 2X 120 watt panels in parallel (on a sailboat - so one may have shade) - should I put a 10 amp blocking diode on each positive before the combiner? So in a boat situation it is not only possible, BUT very likely, that one panel in parallel may be totally blocked by a sail shade..
I have some doubts: 1, The solar strings act like 2 battery cell connected parallel (remember top balance!). Until there is a big enough load the current flows MOSTLY to load. 2, Parallel resistors. The MPPT (and LiFePO4 cells behind it) have very low resistance. The Solar panels have high resistance. So current is flowing through the panels too, but few: R = R1×R2 / (R1+R2) 3, Voltage difference: where there is a potential difference there is current (and bigger makes higher) 4, MPPT is a high frequency DC/DC converter. So it pulsates very fast (open-close) in the solar side. And every time it is open there is an OC (only path through lower V string). 5, You can have a string in East and one on West roof (angle >20). The East is already producing in early morning where the West panels are totally in dark. 6, You can have more than 2 strings parallel. Like 2s6p config for some MPPT's. If one of the strings is in shade then 5 strings will push current through it. 7, Use fuses for the parallel strings. If a short occurs then all the parallel strings production will be going through THAT (lower resistance). Making a big shiny arc (DC so constant arc).
a blocking diode is only needed if one is using a low wattage panel direct to a battery with out a controller lets say for long time vehicle storage to stop the battery discharging into the panel
Please, anybody can help me to explain what is happening. I have a 24V setup with 16 lithium battery, a BMS balancer JKONG and a Powland Inver. My app show a 75% charge,432ah in the battery but the Voltage is down to 23v. ... The inverter is reading 22,1v and prepare to shoot down. Why??
They can produce heat if current goes through them. up to the point where they catch fire. That's why it is important to have the right safety equipment installed.
Would it be a good idea to have a blocking diode if you have more than one string. It could help if one of the strings were hit with lighting or some other high voltage. It would blow the diode. What do you think?
Hei Andy, have u tried to check the 5.5v mini solar power if it glows in the dark? If u feed it with 6v or over you'll have a little bit of surprise 😮😉...
I have 2 X 150 W 22V oct voltage solar panels on each side of my boat. All panels are connected in parallel and charging is controlled via a voltage sensing relay, no charge controller. Would blocking diodes be beneficial for each 2 parallel panels?
do you replace the diode with the same number as the old one like [10amp Diode Axial Schottky Blocking Diodes for Solar Cells Panel,15SQ045 Schottky] [BOJACK 10SQ050 Schottky diode 10 A 50 V axial 10SQ050 10 amps 50 Volts for Solar Panel Parallel reflow Protection diodes] [Bridgold 25pcs 3Types Silicon Rectifier diodes,Package Including:10pcs 6A10 10pcs 10A10 5pcs 20A10] ok which one what volts going on and on
Hi Andy, thank you for the follow-up experiment. Can you please do this easy experiment for us? I also see people started doubting your bypass diode explaination in the comments. In the previous video, you covered 2 of the 3 panels right? Since, the panels have bypass diodes, people will question shouldn't it be producing around 200W from the non-covered panel instead of a mere 30W total? However, as far as I understand your battery system is over 50V and a single panel's Vmpp is less than 40V, is that right? So, the panel can't change your battery, hence the low power output. But if you had covered only one panel, then the potential of the remaining two panels will be high enough to charge your battery and the panels should be able to push 300-400W right? Can you please verify this? Thanks.
@@MatejFabianek The usable power is only from one panel, his system requires at least 2 working panels. Obviously, the voltage we see is added with the voltage from the two shaded panels, and hence producing max 30W (V of panels should be greater than the battery V to charge). Anyways hope Andy will verify this easily and show us. Thanks.
perfect Andy!!! thanks a lot and please remember not all people and eng skills or education :) what is basic for us sometimes is a complete nightmare for others
Thank you, it’s fantastic to find a You tube site that is easy to understand and is interested in teaching the facts about the subject. Question, is it best to use lithium iron sulphate batteries? I have no experience in solar energy I’m hoping to set it up in my outside work shed.
O sea q si lo va poner un inversor o va cargar una batería no es necesario el diodo pero una pregunta porque va el diodo en paralelo con el panel y no en linea recta en el positivo eso es loque yo no entiendo y ya investigue pero encuentro nada al topar puntas del cable del panel siempre se cae el volante así como trae el diodo y de antemano gracias espero me entiendas
Blocking diode (function) will be in any good MPPT controller. Or ANY good controller, to prevent night loss. Installing directly in the panel array would be a waste, as they cause voltage loss, and extra expense.
Thank you for this video. I'm loading up on research before building my first solar power system. So, then, the shading of one or two panels, will not decrease the output of the string, yes? And the same goes for two series strings connected in parallel?
The power out will be proportional to the sunlight falling on them. But unless you have a lot of lead resistance to the CC or inverter, then it will probably be negligible. Do the math.
I'm learning something. Thanks. So my questions is whether your observation regarding the blocking diode holds true between a full load and no load at the charge controller? Thanks again.
Andy, all along, I think the diode inside the solar panel was blocking diodes. You corrected my misconception. Thanks. You said it was not necessary to add blocking diodes since the charge controller had the lowest impedance. Yes, I totally agree with you. But if the battery was fully charged, and the charge controller was in float mode, then the charge controller would not take in any current from the panel. Then panel with a higher voltage will push the current into the lower voltage panel. In this case, will it hurt the lower voltage panel?
Quite a bit of flickering...you might look into changing those lights...Maybe you get a LED driver (Power supply) and connect it to DC LED panels? The LED driver will make sure that you have a smooth DC Voltage without much ripple at the output. Alternatively you could use a DC-DC converter to dirve the LEDs with your battery bank directly.
Love ur videos I've looked at a few my problem is my diodes are reading one way like they supposed to but my panels voltage is in reverse I'm getting a negative -00.1 when I test my panel
All diodes and solar cells act like zener diodes when reverse biased. That includes all semiconductors acting like a solar cell to some degree when exposed to light. If you had thousands of LEDS you could make a solar panel. Although you would need many blocking diodes with one being in each small string, because they can only handle so much voltage before they try to conduct. That was some interesting trivia. Rectifying diodes also will have a much lower effective voltage drop if you put multiples in parallel. PN junctions are weird like that.
you're slightly wrong about all diodes acting like zeners, a zener junction will recover but a normal diode either stays shorted after rv breakdown or burn out
The diode at the back of the solar panel's black box is a bypass diode. Its function is to bypass the panel in case it got damaged (open circuit damage to be exact).
Hey Andy. Good explanation on blocking diodes. I use three of them on my system, but it's very different than your setup. My system is on my Recreational Vehicle and i have three different sources of voltage/current to charge the batteries. I can use the onboard RV charger, i can charge from the tow vehicle, or i can charge from the Solar string. I found that i had to use a blocking diode for each of the three charging systems, as it was possible to be charging the batteries at night and the RV charger would pass current through the solar string. The biggest downside of the blocking diode is the .5v voltage drop that it creates, and the heat that has to be dissipated with the blocking diode. I have a large heat sink on the three blocking diodes to deal with the heat. Anyway, very different application that yours, and the blocking diodes allow me to use all three sources at the same time if i choose to quickly charge the system. Thanks Andy. Good stuff!
Thanks James, very good point and a different scenario. If you have panels with different voltage, you need blocking diodes, that is correct. You can get Shottky diodes which have only a 0.2V voltage drop.
Schottky diodes have a .4 volt drop. Use them for this purpose. Also, your solar charge controller should prevent current from going from your RV charger through the solar string but it depends on how you have it all connected. Seems to me you should only need one diode in the right place.
Don't know why you tube said to watch this video but it did. I did. I use a blocking diode between each string in parallel. I don't know what the failure mode is for a solar panel but if it is shorted, I don't want 50 amps feeding it.
I can see blocking diodes being necessary in an RV/campervan solar system where let's say you park and a tree branch blocks the front of the vehicle but not the back.
Thanks for going over this, I like to hear the basics. I had not used any blocking diodes in my system and noticed that the combiner boxes that they sell come with them so always wondered if I should invest in one of those fancy boxes.
I think they are good for marketing. It all depends a bit on your circumstances and location. If you have a lot of shading during the day, yes, maybe (can you not just install more solar?). If you only have shading in the morning or evening, don't worry about it...
What happens at night in total darkness? Isn't it possible (due to a fault in the Solar Controller) that the battery storage voltage & high current can backfeed into the solar panels and destroy them? Isn't this the reason why every Solar Panel has a diode across the (+) and (-), with the cathode facing the (+) terminal? Also, talking about diodes, if you are drawing any inductive load directly from a Solar Controller, it is wiser to install a blocking diode of a suitable size - simply to protect from back EMF reaching the Solar Controller, with possible resultant damage. This is my understanding, and I hope it makes sense.
*Blocking* *Diodes* are recommended when you connect a Solar Panel directly to the battery, without any Charge Controller. This prevents the battery from discharging through the Solar Panel(s) at night ...
@@MrSummitville It was a gift 10 years ago from my daughter. Surprisingly well designed learning tool/toy for the time. I know a couple offgriders that used them for years as their main electrical power source. Yes, they are wayout dated now, but if it works no need to throw them away. It can run 1 light in a shed or outhouse. I did have to open the panels up after 7 years... break the corners of the glass to resolder the leads back on. Lot of fun, minimally useful.
Love your content! But please fix the flickering when you are in the garage :-) Have a look at 1 min 25 seconds for example. It looks like the fluorescent lights are the ones that make the flickering occur? 50 Hz compensation in the camera? Keep up the good work!!
i think I] will buy this one for 12v solar panel [Ltvystore 30PCS 15Amp Diode Axial Schottky Blocking Diodes Compatible for Solar Cells Panel,15SQ045 Schottky] if you think it is ok please [15a x 12v =180w] I think
Thanks - I was wondering about both of those diodes... answered my question completely!! People should do a little real research in the literature, not U-Toob, before throwing scat.
That didn't make any difference. The LED light above did not had any effect on the PN layer. Not enough lumen I guess. Yeah, that would be another experiment to see what happens when lights hit the panel.
Its best to have the blocking diode, as its not just shaded panels in a string, but also a faulty panel or cell can get very hot if its being back-fed from other parallel strings. Even thou most of the power will go to the charger/inverter some can back-flow through a dark string, if there is a fault, a lot of current can flow and the panels will get very hot. Did u know dark shaded spots on panels will destroy them as current is forced through the shaded cells and they get hot. Remember the roof is very hot as it is.
Back in the early 90s i used 60 watt Solarex panels witch came with no diodes. I installed blocking diodes and ran straight to my batteries. No charge controller.
Great video, but I'm not sure why people are disputing this as blocking diodes are so cheap and they simply plug onto the end of a series string, so if you use them you simply eliminate any possibility of back feeding when shaded so I would rather know all of the power my panels are producing is flowing in the direction of my battery bank.
Simply said, bypass diode is connected between the terminals, blocking diode is connected in series to prevent back-current. Use a diode with lowest voltage drop for best performance
@@OffGridGarageAustralia if we're talking bout bypass, voltage drop does not matter. If we're talking blocking diode, i always choose schottky. The differential between schottky and ceramic one is not marginal. The performance loss is 1W on my 20Wp (schottky vs ceramic) and progress more as you catch the sun on stronger panels
It's not necessary to have a blocking diode on each string if you have very few parallel strings. You don't want to run 80*ISC through one string because its shaded and you have like 100 strings in parallel.
But... this is why one should fuse each panel in a parallel string (depending on how many panels in the string). This is because if a short were to develop in one of the panels, the remaining panels in the parallel string would dump all their amperage into the shorted panel and cause a fire. The fuse should go right on each individual panel that is connected in parallel.
You are mistaken. You do need blocking diodes for older panels, which have a single PV surface. However, modern panels, have blocking diodes included in their internal construction, since you can shade half the panel and still get half the power. I have a bunch of thin film panels (the black ones, where the PV cells are thin and run through their entire length), which DO need a blocking diodes to run in parallel. I found out by experimenting, just like you did.
a diode have a p-n junction, a solar panel have a p-n junction regardless of whether its old or new, here is a challenge, show us one modern panel which have bloking diodes built in
Yes more Booom and Cooouuntact🤣🤣 ... Love it!!!!😎🤘 Andi... Alle Daumen hoch.. Bring Ordnung in das solarchaos.. Und 18650 sind gratis. Probiere das mal.. Die machen süchtig..😆
@@OffGridGarageAustralia ja das kann schon sein... Schade darum hier in Deutschland wird es nur schwieriger sie zu bekommen... Joe seinen Kanal schaue ich von Anfang an... Deinen auch schon ne ganze weile... Und du hast recht, es wird sehr viel Müll geschrieben von Leuten die keine Ahnung haben... Mach weiter so....
@@OffGridGarageAustralia I'd reply with "Yes". Not giving you an answer to either but knowing that I'm on one side or the other (or possibly both sides). :: Chuckles ::
Everything emits IR light even the darkest parts of space. The light emitted is proportional to it's temperature. This is called black body theory or more properly "The Stefan-Boltzmann law".
Love how you set the record strait. Too often these people that say things as gospel don’t get educated and continue to propagate rubbish. I hope it doesn’t cost you subscribes, it’s funny how some people don’t like to be corrected. 👍🏻👍🏻
Andy - interesting experiments, try totally shading the solar cell, then put it in full sunlight and see if the voltage required to back feed current through the solar cell changes? In theory the solar cells output voltage (what ever it is at the time of testing) has to be overcome by your power supply before any current will flow from your power supply? Your solar cell was under quite bright light so it could have been producing a voltage which would explain why it needed higher voltages to back feed current through the cell. Blocking diodes are only needed with parallel strings for example, when one string is facing east and another is facing west so they do not produce power at the same time of day! As your experiments clearly showed parallel strings on a roof in a east then west facing roofs would back feed without blocking diodes on each string. In situations like this it is better to have each string on separate MPPT inputs on your inverter then blocking diode are not needed. :)
When I connected the solar panel to the power supply to start the experiment, you could see the power supply did not show any voltage because the solar panel did not produce any power/voltage. if the panel would have produced say 3V under these conditions, the power supply would have shown these 3V. So the LED light above was not enough to trigger anything apart the 0.2V the power supply showed.
@@OffGridGarageAustralia Andy - what your power supply shows as a voltage will be largely irrelevant because it totally dependent on the impedance of the volt meter and power circuits in the power supply relative to the electromotive force (EMF) and current provided by the solar cell under its ambient light conditions at the time of testing! Presumably these are unknown but low, so if the power supply is actually NOT providing back current and the cell is in near total darkness but still producing its rated voltage when open circuit, when you apply back EMF with your power supply back current will only start to flow only when the EMF produced by the solar cell is overcome by the EMF of the power supply. Which is why you got the result you did with your experiment in my view. By the way, you are right solar cells and solar panels are NOT the same as diodes they act more like battery cells or capacitors than diodes! Blocking diodes exist in parallel string arrays because conditions relating to shading can and do occur that allow back current in a string to rob the total array output of power. Bypass diodes exist in panels to prevent partial shading of one or two cells causing cells to overheat and become a fire danger by becoming a resistive load in the string or panel. In a worst case scenario most of the energy produced by a string can be used to heat just one cell creating what is commonly known as a hot spot on the panel.
You have just enlightened me M8. I had seen the term blocking diode and bypass diode and assumed the two were the same. Thank you.
I have been messing with off grid power for ~10 years and you just set me strait.
Thanks for the feedback, Michael!
Always know you got a bone to pick when you start it out this way. Good stuff Andy, clarification is always a good thing
Solar cells are like Zener diodes, when you exceed their avalanch voltage in the reverse direction, they will conduct.
That is exactly right!
I tried the same .. the solar panel works as a led .... Well its visible through a camera though
Well its not from visable spectrum
@@Riddhi42069 It is, with infrared camera!
That is a really nice way to describe how things work.
I already knew the basis but still really enjoyed watching your video.
Totally agree that in your scenario you’re unlikely to require a diode.
I wonder if I might though, as I’ll be building a solar fence where at times many panels won’t be in the sunlight so maybe that would yield different results.
I’ll certainly film a test against that and see if it also works just fine without diodes.
I’ll then also compare the diodes with Tigo optimisers as I haven’t really seen such a test but I think they go hand in hand when you look at how those optimisers work.
Thanks for another good video!
Solar diode manufacturers, welcome to know
Good video, very well explained re solar panels wired in series, but what about those wired in parallel? I have 3 panels (1x100W, plus 2x 160W) charging 12V AGM batteries for shed power. The 100W faces SSE, and both 160W panels face due South. One of the 160W panels is shaded each morning by a neighbours tree. Should I install a MC4 type blocking diode in the positive cable of each panel output?
You are right, in my first built east west 5KW unit I measured zero current running in the shaded part when the sun still was
bright at the west side. Diodes produce losses, 0.7V siliciums
I would add only that a solar panel acts as diode ONLY in that when power is pushed to the panel it becomes an LED (light emitting diode), however the light emitted is not in the visible spectrum. Thanks for giving me some good laughs when you responded to people's comments though. Although I have a feeling those types of comments will never stop, lol. Great video, cheers. 😎
Thanks for your feedback and additional comments.
I have a question sir.
I have all in one off Grid solar inverter which supports 3.5 KW panels. So there are 3 strings os 3 panels each that make up 3.5Kw. all 3 strings are parallel. Will it Be a problem If I place 2 strings iñ south direction and 1 string in West direction? Your reply will be appreciated.
The reason for this is to get some power and try to keep the batteries topped up untill the sun goes down.
Thanks
That depends on how many solar inputs the inverter has. If it has only one solar input, I would not recommend mixing strings which point in different directions.
@@OffGridGarageAustralia thanks for quick reply sir.
Inverter has only one input channel.
What blocking diode would you recommend for a 100watt 12 panel. I have shade problems currently and panels in different locations. A part number would be great. Great video.
12:17 what happens if the input door, in the solar charger controller, is closed because battery is full?
It does not turn off the charge controller, there is no switch or relay. When the battery gets full and the charge controller reduces power it just drives the panels away from the maximum power point, into an inefficient area of the solar panel curve so to speak. It will not disconnect the panels though.
@@OffGridGarageAustralia thanks for the answer and for the time you spend to give us free learning content.
You, Will Prowse, David Poz and Jehu Garcia are the best solar teacher in the globe!
I have 4 panels 2x2 in series and both strings in paralel on both sides of my balcony. In the morning the sun is from one side than after 12 o clock fron the other. ON EACH SERIES strin one panel stoped working and I am wondering why. I do not haveb a blocking diode
Very good experiment and explanation. That confirms what i had thought regarding diodes and back current. Earlier today, i found som facts about solar cell tecnique, and read that a solar cell is a type of diode. But the current created by sunlight flows in back- direction of the diode/solarcell. That should explain why the solarcell does not block ” back-current” Back current in the way we ar speaking about will flow in forward direction thru the diode/solarcell.
I'm sorry if I'm a newbie, but the way i understood is, blocking diode and bypass diode is the same, it's just the way it is connected that makes it a bypass or blocking. if its connected in parallel in between the + and - in a pv array then it acts as a bypass diode. if it's connected only in the + of the PV in a one way strean of power flow then it wll act as a blocking diode. am i correct? please respond.
Physically, they are the same diodes, that is correct.
Yes, you're correct. Bypass diodes are across the single strings in a panel to prevent total power loss during shading, while blocking diodes protect the panels from current flowing backwards.
or in the -ve of the panel
Hi. If I have only 3 panels, in parallel, the internal bypass diode act as a block diode. Correct? I understand Well?
kindly guide me as my 150watt solar panel is showing 21volts but 1.2 amp. What should i do and what is the reason.?
11:00 Solar Panels can become a regular LED emitting light too (when it consumes current).
We dont see it because the light is extremely faint.
that may be true but show us a situation where one panel would be it total darkness while the other is in lighted area. even in shaded area the solar panel is still producing
Hey Andy I need some help with bypass diodes I was given some panels and one of them the center bypass diode was accidentally broken off any ideas how to find out what one I would need to replace it with I’m talking about the one on the back of the panel in the center junction box the whole box is gone but the terminal tabs are intact
If you look at the label on the panel it should tell you the short cct current, ideally the diode should be able to handle that current
A panel of mine was shorted and now when I try to connect to battery it asks what should I do
So here is my question. If I have 2X 120 watt panels in parallel (on a sailboat - so one may have shade) - should I put a 10 amp blocking diode on each positive before the combiner? So in a boat situation it is not only possible, BUT very likely, that one panel in parallel may be totally blocked by a sail shade..
I have some doubts:
1, The solar strings act like 2 battery cell connected parallel (remember top balance!). Until there is a big enough load the current flows MOSTLY to load.
2, Parallel resistors. The MPPT (and LiFePO4 cells behind it) have very low resistance. The Solar panels have high resistance. So current is flowing through the panels too, but few:
R = R1×R2 / (R1+R2)
3, Voltage difference: where there is a potential difference there is current (and bigger makes higher)
4, MPPT is a high frequency DC/DC converter. So it pulsates very fast (open-close) in the solar side. And every time it is open there is an OC (only path through lower V string).
5, You can have a string in East and one on West roof (angle >20). The East is already producing in early morning where the West panels are totally in dark.
6, You can have more than 2 strings parallel. Like 2s6p config for some MPPT's. If one of the strings is in shade then 5 strings will push current through it.
7, Use fuses for the parallel strings. If a short occurs then all the parallel strings production will be going through THAT (lower resistance). Making a big shiny arc (DC so constant arc).
The characteristics of the solar strings are very different to 2 batteries in parallel. They don't just try to balance each others voltage.
That's what I feel is happening too! Andy is a great engineer and all, but not so hard on the science part.
a blocking diode is only needed if one is using a low wattage panel direct to a battery with out a controller lets say for long time vehicle storage to stop the battery discharging into the panel
Yes, that would be a case for such a blocking diode. Great example.
You did a wonderful job explaining this andy. Thanks.
Does the charge controller act as blocking diode.?
Please, anybody can help me to explain what is happening. I have a 24V setup with 16 lithium battery, a BMS balancer JKONG and a Powland Inver. My app show a 75% charge,432ah in the battery but the Voltage is down to 23v. ... The inverter is reading 22,1v and prepare to shoot down. Why??
Immer wieder gut!
Danke Dir!
What if you change the polarity on the solar cell and the bench power supply. How the cell will behave then?
Min. 8:35 , Can the solar panel produce heat ? If so ..., how much ?
They can produce heat if current goes through them. up to the point where they catch fire.
That's why it is important to have the right safety equipment installed.
Would it be a good idea to have a blocking diode if you have more than one string. It could help if one of the strings were hit with lighting or some other high voltage. It would blow the diode. What do you think?
I did another video on this with a test. Blocking diodes are not necessary. th-cam.com/video/NaCOdOdhdTY/w-d-xo.html
Hei Andy, have u tried to check the 5.5v mini solar power if it glows in the dark? If u feed it with 6v or over you'll have a little bit of surprise 😮😉...
I need to replace my junction box( diodes), do all cell use basically have the same diodes
They have probably different diodes depending on the panel's voltage and current.
thanks for the video. it explained the difference between the two types of diodes very well. thanks
I have 2 X 150 W 22V oct voltage solar panels on each side of my boat.
All panels are connected in parallel and charging is controlled via a voltage sensing relay, no charge controller.
Would blocking diodes be beneficial for each 2 parallel panels?
wouldnt it makes more sense to get a solar controller than worry about blocking diodes? I'm sure your batteries would benefit more
do you replace the diode with the same number as the old one like [10amp Diode Axial Schottky Blocking Diodes for Solar Cells Panel,15SQ045 Schottky] [BOJACK 10SQ050 Schottky diode 10 A 50 V axial 10SQ050 10 amps 50 Volts for Solar Panel Parallel reflow Protection diodes] [Bridgold 25pcs 3Types Silicon Rectifier diodes,Package Including:10pcs 6A10 10pcs 10A10 5pcs 20A10] ok which one what volts going on and on
Hi Andy, thank you for the follow-up experiment. Can you please do this easy experiment for us? I also see people started doubting your bypass diode explaination in the comments. In the previous video, you covered 2 of the 3 panels right? Since, the panels have bypass diodes, people will question shouldn't it be producing around 200W from the non-covered panel instead of a mere 30W total? However, as far as I understand your battery system is over 50V and a single panel's Vmpp is less than 40V, is that right? So, the panel can't change your battery, hence the low power output. But if you had covered only one panel, then the potential of the remaining two panels will be high enough to charge your battery and the panels should be able to push 300-400W right? Can you please verify this? Thanks.
I think his bypass diodes have failed.
@@MatejFabianek No I don't think so. As I said, only one panel isn't enough to charge his 50V battery. Andy can verify by covering only 1 panel.
@@DSmartLife his Victron app shows 30W/75V and later 14W/66V on the input from solar
@@MatejFabianek The usable power is only from one panel, his system requires at least 2 working panels. Obviously, the voltage we see is added with the voltage from the two shaded panels, and hence producing max 30W (V of panels should be greater than the battery V to charge). Anyways hope Andy will verify this easily and show us. Thanks.
perfect Andy!!! thanks a lot and please remember not all people and eng skills or education :) what is basic for us sometimes is a complete nightmare for others
How do u increase current in series arrangement of solar panel?
Question please.
What kind of diodes or how to know if what's fit to my 20w solar panels. Thank you. :)
assuming the manufacturer of the panel knows what they are doing they would have fit the correct one
Thank you, it’s fantastic to find a You tube site that is easy to understand and is interested in teaching the facts about the subject.
Question, is it best to use lithium iron sulphate batteries?
I have no experience in solar energy I’m hoping to set it up in my outside work shed.
Is the blocking diode needed if you occasionally feed a grid tie inverter with batteries? (Which puts your battery pack and panels in parallel.)
O sea q si lo va poner un inversor o va cargar una batería no es necesario el diodo pero una pregunta porque va el diodo en paralelo con el panel y no en linea recta en el positivo eso es loque yo no entiendo y ya investigue pero encuentro nada al topar puntas del cable del panel siempre se cae el volante así como trae el diodo y de antemano gracias espero me entiendas
Thanks Andy, didn’t know the difference between the two, but you were able to explain this “basic stuff” perfectly.
Thanks, Tom.
Blocking diode (function) will be in any good MPPT controller. Or ANY good controller, to prevent night loss. Installing directly in the panel array would be a waste, as they cause voltage loss, and extra expense.
I am hoping the video maker will address your comment. TY
There is no night loss on ANY good solar charge controller. They don’t mix their input and outputs.
Thank you for this video. I'm loading up on research before building my first solar power system.
So, then, the shading of one or two panels, will not decrease the output of the string, yes? And the same goes for two series strings connected in parallel?
The power out will be proportional to the sunlight falling on them. But unless you have a lot of lead resistance to the CC or inverter, then it will probably be negligible. Do the math.
I'm learning something. Thanks. So my questions is whether your observation regarding the blocking diode holds true between a full load and no load at the charge controller? Thanks again.
That should make no difference, Harold.
is blocking diode and bypass diode same type of diode ? ordo you have to buy two different diodes to make those connections ?
Same type of diodes but different task.
Blocking diode and bypass Diode is the same diode?
But what size do I use i need one for my dump on my turbines can someone help me
Aim from Kenya Africa thanks you Soo much for your instructions
Thank you Adhan!
do not want to burn my 12v solar panel or battery up please help me
Your explanations are so clear ! As always. Thank you for that
Andy, all along, I think the diode inside the solar panel was blocking diodes. You corrected my misconception. Thanks. You said it was not necessary to add blocking diodes since the charge controller had the lowest impedance. Yes, I totally agree with you. But if the battery was fully charged, and the charge controller was in float mode, then the charge controller would not take in any current from the panel. Then panel with a higher voltage will push the current into the lower voltage panel. In this case, will it hurt the lower voltage panel?
A video of Andy sluicing down a couple of beers... and oh yeah, some good information on by-pass vs blocking diodes :)
After reading all the comments yesterday and repeating myself 100+ times, it was time for a 🍺
Quite a bit of flickering...you might look into changing those lights...Maybe you get a LED driver (Power supply) and connect it to DC LED panels?
The LED driver will make sure that you have a smooth DC Voltage without much ripple at the output.
Alternatively you could use a DC-DC converter to dirve the LEDs with your battery bank directly.
Very good information
Junction box diodes are bypass diodes that prevent shaded cells in series with unshaded cells from being heavily reverse biased under load.
Love ur videos I've looked at a few my problem is my diodes are reading one way like they supposed to but my panels voltage is in reverse I'm getting a negative -00.1 when I test my panel
All diodes and solar cells act like zener diodes when reverse biased. That includes all semiconductors acting like a solar cell to some degree when exposed to light. If you had thousands of LEDS you could make a solar panel. Although you would need many blocking diodes with one being in each small string, because they can only handle so much voltage before they try to conduct. That was some interesting trivia. Rectifying diodes also will have a much lower effective voltage drop if you put multiples in parallel. PN junctions are weird like that.
Hadn't heard that in general about diodes... too bad you can't parallel 10 of them and get 0.04 to 0.07Vf! Worth an experiment.
you're slightly wrong about all diodes acting like zeners, a zener junction will recover but a normal diode either stays shorted after rv breakdown or burn out
The diode at the back of the solar panel's black box is a bypass diode.
Its function is to bypass the panel in case it got damaged (open circuit damage to be exact).
Hey Andy. Good explanation on blocking diodes. I use three of them on my system, but it's very different than your setup. My system is on my Recreational Vehicle and i have three different sources of voltage/current to charge the batteries. I can use the onboard RV charger, i can charge from the tow vehicle, or i can charge from the Solar string. I found that i had to use a blocking diode for each of the three charging systems, as it was possible to be charging the batteries at night and the RV charger would pass current through the solar string. The biggest downside of the blocking diode is the .5v voltage drop that it creates, and the heat that has to be dissipated with the blocking diode. I have a large heat sink on the three blocking diodes to deal with the heat. Anyway, very different application that yours, and the blocking diodes allow me to use all three sources at the same time if i choose to quickly charge the system. Thanks Andy. Good stuff!
Thanks James, very good point and a different scenario. If you have panels with different voltage, you need blocking diodes, that is correct. You can get Shottky diodes which have only a 0.2V voltage drop.
Schottky diodes have a .4 volt drop. Use them for this purpose. Also, your solar charge controller should prevent current from going from your RV charger through the solar string but it depends on how you have it all connected. Seems to me you should only need one diode in the right place.
Thanks for your vids!
It seems the solar panel works as a overpriced resistor in this instance?
Don't know why you tube said to watch this video but it did. I did. I use a blocking diode between each string in parallel. I don't know what the failure mode is for a solar panel but if it is shorted, I don't want 50 amps feeding it.
I can see blocking diodes being necessary in an RV/campervan solar system where let's say you park and a tree branch blocks the front of the vehicle but not the back.
God bless your patience.
Thanks for going over this, I like to hear the basics. I had not used any blocking diodes in my system and noticed that the combiner boxes that they sell come with them so always wondered if I should invest in one of those fancy boxes.
I think they are good for marketing. It all depends a bit on your circumstances and location. If you have a lot of shading during the day, yes, maybe (can you not just install more solar?). If you only have shading in the morning or evening, don't worry about it...
@@OffGridGarageAustralia Thanks nice to see it tested in real life.
Good vid. New subscriber earned!
Keep up the great content!
Cheers, Mate!
- Jesse
Thank you Jesse!
What happens at night in total darkness? Isn't it possible (due to a fault in the Solar Controller) that the battery storage voltage & high current can backfeed into the solar panels and destroy them? Isn't this the reason why every Solar Panel has a diode across the (+) and (-), with the cathode facing the (+) terminal? Also, talking about diodes, if you are drawing any inductive load directly from a Solar Controller, it is wiser to install a blocking diode of a suitable size - simply to protect from back EMF reaching the Solar Controller, with possible resultant damage. This is my understanding, and I hope it makes sense.
*Blocking* *Diodes* are recommended when you connect a Solar Panel directly to the battery, without any Charge Controller. This prevents the battery from discharging through the Solar Panel(s) at night ...
I hand an old HF charge controller that discharged the battery over night. This charge controller needed a blocking diode.
Yes, that is a use case for a blocking diode.
@@petercamusojr1545 "Harbor Freight" for PV components? Well, that tells me all that I need to know ...
@@MrSummitville It was a gift 10 years ago from my daughter. Surprisingly well designed learning tool/toy for the time. I know a couple offgriders that used them for years as their main electrical power source. Yes, they are wayout dated now, but if it works no need to throw them away. It can run 1 light in a shed or outhouse. I did have to open the panels up after 7 years... break the corners of the glass to resolder the leads back on. Lot of fun, minimally useful.
And diode bypass?
Love your content! But please fix the flickering when you are in the garage :-) Have a look at 1 min 25 seconds for example. It looks like the fluorescent lights are the ones that make the flickering occur? 50 Hz compensation in the camera? Keep up the good work!!
Thank you! You're bit behind with the videos. All fixed quite a while back 😊
i think I] will buy this one for 12v solar panel [Ltvystore 30PCS 15Amp Diode Axial Schottky Blocking Diodes Compatible for Solar Cells Panel,15SQ045 Schottky] if you think it is ok please [15a x 12v =180w] I think
Thanks - I was wondering about both of those diodes... answered my question completely!! People should do a little real research in the literature, not U-Toob, before throwing scat.
Nice experiment. What are the voltages and current flows with the solar cell turned face down?
That didn't make any difference. The LED light above did not had any effect on the PN layer. Not enough lumen I guess. Yeah, that would be another experiment to see what happens when lights hit the panel.
Good subject!!!! Thanks👍👍👍 Buddy.
Great explanation. My double is cleared now 👍👍 thanks
Some brands has both blocking and bypass...you can see that on the connection...blocking diodes are in series and bypass diodes are in parrallel
Its best to have the blocking diode, as its not just shaded panels in a string, but also a faulty panel or cell can get very hot if its being back-fed from other parallel strings. Even thou most of the power will go to the charger/inverter some can back-flow through a dark string, if there is a fault, a lot of current can flow and the panels will get very hot. Did u know dark shaded spots on panels will destroy them as current is forced through the shaded cells and they get hot. Remember the roof is very hot as it is.
Back in the early 90s i used 60 watt Solarex panels witch came with no diodes.
I installed blocking diodes and ran straight to my batteries.
No charge controller.
Great video, but I'm not sure why people are disputing this as blocking diodes are so cheap and they simply plug onto the end of a series string, so if you use them you simply eliminate any possibility of back feeding when shaded so I would rather know all of the power my panels are producing is flowing in the direction of my battery bank.
a 50 amps diode is so cheap and its got zero forward resistance
Well now ill need a beer...after all these years being wrong.
No problem, have a beer! 🍺
I was right, but I am having one too.
Simply said, bypass diode is connected between the terminals, blocking diode is connected in series to prevent back-current. Use a diode with lowest voltage drop for best performance
The voltage drop or power loss is actually not much different between a normal diode or a Schottky for example.
@@OffGridGarageAustralia if we're talking bout bypass, voltage drop does not matter. If we're talking blocking diode, i always choose schottky. The differential between schottky and ceramic one is not marginal. The performance loss is 1W on my 20Wp (schottky vs ceramic) and progress more as you catch the sun on stronger panels
I think you should add a weather report in terms of amps.
i read shading causes fires as it overheats panels
Hi!
If you use the mppt, that is not giving back the power.
It is my infomation.
Haw a nice day!
Keep up the educative content, Sir. I've learnt a lot from your channel.
Simply superexcellent video ; )
Thank you very much.
Thanku geezer 😜. Very informative.
Great video! Just with this one, I have become a fan. Question: Why are there specifications of junction boxes with 2, 3, 4, 6 diodes?
Diodes can only pass so much current without overheating, so putting more in parallel splits the current to reduce heat.
@@TheRealMonnie Thank you for the reply! : )
perfect Andy!!! thanks a lot
It's not necessary to have a blocking diode on each string if you have very few parallel strings.
You don't want to run 80*ISC through one string because its shaded and you have like 100 strings in parallel.
But... this is why one should fuse each panel in a parallel string (depending on how many panels in the string). This is because if a short were to develop in one of the panels, the remaining panels in the parallel string would dump all their amperage into the shorted panel and cause a fire. The fuse should go right on each individual panel that is connected in parallel.
short across 1 panel is very unlikely scenario.
Thumbs up and subscribed! Definitely learned , good interesting 👍
Now i got it, why not to Mount EM parallel but allways in a row.i guess you did know about the UV light
Problem occurs when one cèll is blocked by leaves in a panel
Great video. Thank you very much.
You are mistaken. You do need blocking diodes for older panels, which have a single PV surface. However, modern panels, have blocking diodes included in their internal construction, since you can shade half the panel and still get half the power. I have a bunch of thin film panels (the black ones, where the PV cells are thin and run through their entire length), which DO need a blocking diodes to run in parallel. I found out by experimenting, just like you did.
a diode have a p-n junction, a solar panel have a p-n junction regardless of whether its old or new, here is a challenge, show us one modern panel which have bloking diodes built in
Every video is getting funnier as average joe... good move and good explanation
Very clear explanation
That BOOOM Made my DAY!!!💥😆🤘
Just wait for the shirt 😊💥
Yes more Booom and Cooouuntact🤣🤣 ... Love it!!!!😎🤘
Andi... Alle Daumen hoch.. Bring Ordnung in das solarchaos..
Und 18650 sind gratis. Probiere das mal.. Die machen süchtig..😆
@@ennyw20 18650 gibt's hier kaum. Die wandern alle auf die Deponie. 😒
@@OffGridGarageAustralia ja das kann schon sein... Schade darum hier in Deutschland wird es nur schwieriger sie zu bekommen...
Joe seinen Kanal schaue ich von Anfang an... Deinen auch schon ne ganze weile... Und du hast recht, es wird sehr viel Müll geschrieben von Leuten die keine Ahnung haben... Mach weiter so....
@@ennyw20 vielen Dank!
Thank you for taking the time to unconfuse the confused and to confuse the unconfused. Haha, SMILEY FACE
Hahaha, which side are you on now?
@@OffGridGarageAustralia I'd reply with "Yes". Not giving you an answer to either but knowing that I'm on one side or the other (or possibly both sides). :: Chuckles ::
With an infrared camera when you pass current through a solar panel it emits IR light
Everything emits IR light even the darkest parts of space. The light emitted is proportional to it's temperature. This is called black body theory or more properly "The Stefan-Boltzmann law".
Love how you set the record strait. Too often these people that say things as gospel don’t get educated and continue to propagate rubbish. I hope it doesn’t cost you subscribes, it’s funny how some people don’t like to be corrected. 👍🏻👍🏻
Well, look at the video before how many people got it wrong. If they cannot handle the truth, well... I explained it in all details.
Andy - interesting experiments, try totally shading the solar cell, then put it in full sunlight and see if the voltage required to back feed current through the solar cell changes? In theory the solar cells output voltage (what ever it is at the time of testing) has to be overcome by your power supply before any current will flow from your power supply? Your solar cell was under quite bright light so it could have been producing a voltage which would explain why it needed higher voltages to back feed current through the cell. Blocking diodes are only needed with parallel strings for example, when one string is facing east and another is facing west so they do not produce power at the same time of day! As your experiments clearly showed parallel strings on a roof in a east then west facing roofs would back feed without blocking diodes on each string. In situations like this it is better to have each string on separate MPPT inputs on your inverter then blocking diode are not needed. :)
When I connected the solar panel to the power supply to start the experiment, you could see the power supply did not show any voltage because the solar panel did not produce any power/voltage. if the panel would have produced say 3V under these conditions, the power supply would have shown these 3V. So the LED light above was not enough to trigger anything apart the 0.2V the power supply showed.
@@OffGridGarageAustralia Andy - what your power supply shows as a voltage will be largely irrelevant because it totally dependent on the impedance of the volt meter and power circuits in the power supply relative to the electromotive force (EMF) and current provided by the solar cell under its ambient light conditions at the time of testing! Presumably these are unknown but low, so if the power supply is actually NOT providing back current and the cell is in near total darkness but still producing its rated voltage when open circuit, when you apply back EMF with your power supply back current will only start to flow only when the EMF produced by the solar cell is overcome by the EMF of the power supply. Which is why you got the result you did with your experiment in my view. By the way, you are right solar cells and solar panels are NOT the same as diodes they act more like battery cells or capacitors than diodes! Blocking diodes exist in parallel string arrays because conditions relating to shading can and do occur that allow back current in a string to rob the total array output of power. Bypass diodes exist in panels to prevent partial shading of one or two cells causing cells to overheat and become a fire danger by becoming a resistive load in the string or panel. In a worst case scenario most of the energy produced by a string can be used to heat just one cell creating what is commonly known as a hot spot on the panel.