60% Solar Panel degradation? Just why? Troubleshooting Part 1

[@timos144]

When i use used panels, i check diodes, voltage and short-circuit current on all of them individually before installing them. I think that's coming to you now too. not meant badly, but now there are more videos of you that can help others too :)

[@habana7638]

Old different panels, different types of mc4 connectors, what to say about that ridiculous ceiling junction box (Sorry Andy), what can you expect, my advice would be also to test all panels separately and replace all mc4 connectors and make that junctionbox as it should be..

[@PatricksDIY]

Since its really hot outside, the heat may be effecting the output, If you can, try spraying your hose or dumping buckets of water over them, to see if its the efficiently due to heat. Just an idea, I cant think of anything else at the moment.

[@andresgodinho]

This is what i was going to sugest!!

[@OffGridGarageAustralia]

It's not really hot, it's autumn now and mild.

[@andresgodinho]

@@OffGridGarageAustralia my solar panels were from dubious sources and they claim 2.1kwp... here in Portugal it is 15 °C outside and full Sun, sollar irradiance is 900 W/m2 and they output 1.1 kWp max! If i shower them or if clouds pass by, they go up to 1.7 kWp .. the cells in my panels seam craked and i think that with the Heat they expand and have Higher internal resistance

[@PatricksDIY]

@@OffGridGarageAustralia I forget you are in a different season people in the US :)

[@michaelrobinson3935]

Andy I had the same problem with my panels , it turned out to be the Mc connectors . You have to use the same brand of connector there not all the same. I noticed the last panel you plugged in didn’t go all the way in the white o ring was still showing.

[@OffGridGarageAustralia]

Great, thank you. I have replaced some MC4 were they were cut off, but now all of them. Some go really hard, some easy. I always thought it's because of the O-ring. Some WD40 on that ring and the problem was solved.

[@mattiasjansson1565]

My guess is bad connection in the old plugs or cables. Once I had jumper-cables that visually looked good that were only clamped to the jaws and didn't even conduct enough current to run the interior light on the depleted car. I soldered them and now they work just fine. Good luck Andy, and thanks for always trying to learn more! Hope you have a nice cold beer after! Cheers from Sweden!

[@cristof48]

hello from France, it's look like if one panel in each string was reverse polarity. May be you have reverse MC4 connectors when you crimp them ?

[@kevinmills5293]

If that were the case, VOC would be around 45V.

[@peterrock2838]

I love the troubleshooting... You have problems (and solutions) that help us all. Thanks for including your subs into the problem. The comments are interesting. You have a very smart set of subs! - I have to go with testing panel output individually to find the faulty one that is absorbing the energy from the others.

[@cfeigel]

Frustrating, I know! If it turns out to be the panels, I'll just point out: 635w / $FREE = a pretty good ratio!

[@zarbonida]

Try to cut and changing solar wire connection (from the panels). The copper in the wires, after ten years, could be oxided

[@69nites]

3 strings running through the same wires reading low voltage and amperage. I'd say the wires would be my first thought as well. I'd swap to the cables from the other side and see before anything else.

[@chiefkeith5641]

If you’re saying cut the panel wires that’s a terrible suggestion. It’s almost never the panels

[@craigivas4037]

Hey Andy if everything was fine yesterday it ll be the heat i have the same problem here in Perth. When its hot I turn my panels away from the sun and they produce far more. I do have a dual axis tracker fitted to mine. I have two panels parallel and produce about 4kw a day.

[@marcfontaine8596]

Diffrent brands in series do not have the same amp rating. The max string amp will be limited by the lowest amp capacity panel.

[@BastelPichi]

Yes. But they have the same amp ratings, Sherlock

[@kevinroberts781]

I'd call up the installer and demand he fix it! That is nuts!!

[@edwardvanhazendonk]

Wow, 1 hour after posting you already have 1 answer per minute, more than I can think of, good luck and plans for finding the cause, always good if people chime in to give feedback on questions, great bunch around here!

[@millzee60]

Failed diode or maybe reversed polarity? :) But on each of three separate strings. Hmm.

[@OffGridGarageAustralia]

Exactly. One panel faulty, yes, maybe two. But all of them, three different brands and types? That's like a good lotto win, right!?

[@vaneay]

@@OffGridGarageAustralia just need one bad on each string ( murphy law) :P

[@edwardvanhazendonk]

Also check the cables for the current, on top of the shed, maybe 1 string doesn't carry current. You have the correct power clamp for this. And sorry to hear it's not working

[@AveRage_Joe]

When the inverter kicks on and im near it working on things it scares the 🐈 out of me to lol💥

[@OffGridGarageAustralia]

And it always happens when you just plug in cable somewhere ⚡

[@electrodacus]

Both max power point voltage and open circuit voltage will be much lower that STC spec as panels are hot so that is not a problem. But the current should be about 2x larger than what you see so no idea what the problems is as it is not making much sense unless at least one panel in each string has some cracked cells.

[@OffGridGarageAustralia]

I know I'm nut running in STC and voltage and current are lower. But that low does not make any sense, right. Also with three different types of panels... More testing coming.

[@electrodacus]

@@OffGridGarageAustralia My best guess is that panels where abused (maybe thrown of the roof when uninstalling so they have cracked cells). STC is measured with panels at +25C but of course your panels are likely at 65 to 70C so that open circuit voltage of around 39V is totally normal. Current on the other hand should be a lot higher and the only way to check will be to test each individual panel maybe only some of them have cracked cells. It is sure not the degradation that is responsible as that will be in average just 0.5% per year so even if those were 10 years old it will not be more than 5% degradation.

[@craigivas4037]

Also Andy check your battery voltage. As your batterys get full the controller regulates input from the panels ... maybe...

[@OffGridGarageAustralia]

Battery is at 60%. As shown in the video, the east side is on full blast charging.

[@petermac9304]

Check the mc4 box, I have the same problem. When I open it up, one of the soldering came off. Soldering it back and work perfect. You can also check each panel voltage that is how I found out my panels is not working right.

[@OffGridGarageAustralia]

I thought about that, but we have the same fault on all panels??? 6x Suntech, 2x RenesSola, 1x TNS Solar? How high is that chance?

[@zarbonida]

@@OffGridGarageAustralia did they come from the same roof?

[@jmaus2k]

@@OffGridGarageAustralia Actually a very high chance. Probably the only thing that actually fails with panels is this connection. They get hot, melt solder, and disconnect. Use a crimp connection to avoid future issues.

[@philipmorgan1438]

The old panels were stored for years right? I wonder if the MC4 connectors on each panel are crimped vs soldered? Have to wonder about condensation and corrosion inside the connectors!

[@OffGridGarageAustralia]

That is a good point. I had actually some older MC4 plugs with a few cm cable attached, which were cut off panels when they took the system down and some of them were so poorly crimped, the cable just came out of the plug when I pulled on it. I think they didn't use the correct crimper but just some pliers.

[@philipmorgan1438]

@@OffGridGarageAustralia It seems that, if the panel voltages are about right, and current output isn’t correct, there’s high resistance interfering with flow on each panel. That makes the MC4 connections prime suspects IMO. Good luck with checking it out soon.

[@andrewsweet43]

Just a wild guess. Maybe the bypass diodes on these panels can't deal with the higher voltage of the 3 panels in series, or had a rough previous life (maybe lightning strike closeby?) and one of them shorted, resulting to one panel not contributing to the string. Check the diodes and for signs of corrosion on the cables! Also try cooling the string down with water to measure the effect of heat on the panels. Furthermore, if the panels are mismatched, the resulting I-V curve may have more than one "knees" (mpp points) which may confuse the charge controller and chose the wrong point as a MPP point...

[@infinitygreenpower]

The problem because the PID. As you said that these PV panels are used and 10 years old , so if you bought it as used for about 10 years ago then I think some of them had PID Problem ( Potential Induced Degradation) the old PV panels design was without Free-PID protection and because the connect it in series with more than 500VDC and with high temperature and humidity this within about 5 years or more will do a degradation of the pv power and will kill the efficiency and the pv panel will generate about 50% maximum power. Therefore many companies and projects that using old PV panels They started discarding the solar panels and selling them cheaply because they became damaged due to the PID. Now days all new factories produce the PV panels with Free-PID and Free-LID.

[@zarbonida]

Good to know. Thanks

[@Useitorloseit1]

Andy, figured out how I can catch up to your videos. Need more monitors, that will do it, 3 Andy's at once, perfect!

[@khalilullahyosufi9379]

In 2008 I bought 3 mono crystalline panels and soon I found that the panels work so bad when the sun light does not optimized in front of the panels. So last year I decided to buy some 18 poly crystalline panels 346 Watt each although I studied that the mono crystalline panels are more efficient than the poly crystalline.

[@jadu79]

what I thought I saw was that the Volts at MPPT changed and they sound from 60 + v to 80v depending on the string and it should in my mind change a lot in the result. Then well ages were more "optimized" for 1000w / m2 and gave poorly when it became smaller, which is also the case if they are not completely aimed at the sun

[@villacarinaapartments]

I think that you have a burnt bypass diode in each string. Check every individual panel voltage and short current.

[@sinusgolf]

I would buy one brand new top grade panel and compare this with the old ones 😊👍

[@jmaus2k]

The voltage varies with temperature. With those cells at 55C (assume warming from the sun) - STC at 25C is a 30C rise. 30 x 0.34%/C * 45.2 = -4.6V when warm. So the string new would read about 121.8V. Used could be 90% of that and 109.6V. Panels are not perpendicular to the sun either like how the testing is done. So 115V is right on the money and would be expected.

[@ursmalo3103]

Maybe high resistance in the connection plugs of the panels?

[@OffGridGarageAustralia]

I replaced some of the MC4 connectors, but not all...

[@nigeldunn4467]

Hi Andy, All it will take is one faulty panel or component in each string to degrade the output power. The problem with used panels is that it is likely there were technical problems with them or they would still be in service where they were initially installed. Unless you know the service history and condition of each panel, you will need to test each panel separately to establish their current individual condition. The panels could have aged and developed hotspots , it could also be due all the panels underperforming due to the high ambient temperatures on your hot roof! Or it could be bypass diodes leaking reverse current and acting as resistive loads in each string? You will only determine the problem by doing the hard work to find the fault. If all panels individually test the same and appear as normal then it is probably the high ambient temperature on the roof adversely effecting the old used panels!

[@OffGridGarageAustralia]

I don't think it's the temperature. The panels on the other roof side are working fine and even through summer with 40°+ they worked above their specs. No, we have autumn and much milder temps. I need to test them individually, I guess.

[@nigeldunn4467]

@@OffGridGarageAustralia Andy you have been exceedingly lucky with your used east side panels producing more than their rated output at times! As was mentioned by someone before - I would be suspicious of any panel the leads where cut off as it might be deliberate to discourage the re-use of faulty panels?

[@OffGridGarageAustralia]

@@nigeldunn4467 they don't test the panels when they take down such a system. The installer gets paid by the job, not time. So he works s quickly and efficient as possible. If some MC4s are hard to disconnect, they just cut the cables. That does not mean that these labels haven't been handled roughly at this process.

[@peterevenhuis2663]

The heat can affect the panels, but in my case I found water entered the connection box below one panel and corroded the connection. After some cleaning and soldering the panels all work as expected again

[@OffGridGarageAustralia]

OK, there is the possibility this happened to several of these panels, even they come from different source. But how high is this chance? I'll check anyway...

[@williambuehler2784]

It will take some time, but go to your original plan and test each panel separately as you stated earlier. That way you know how each will perform. Also how close are the voltage output of the panels?

[@yodab.at1746]

I'm assuming that the panels are fully loaded and the charge controller is not throttling back due to batteries being nearly upto capacity. Check all connections, check all diodes and if you can, check for hot spots that may indicate micro cracks in the individual cells caused by panel flexing (probably caused by handling before the installation) I have noticed on my rig that the panel temperature has a fairly big impact on generation, my system is best before summer when you have good sun but low ambient temp. Last summer I thought something had gone wrong, I was missing a third of expected current output, but it was panel temperature causing it.

[@OffGridGarageAustralia]

I know, the panels are not in ideal test conditions, but we're not in summer any more and have moderate temperatures now. East roof is doing fine and shows around 15% less power output now than in summer due to the angle of the sun.

[@KevIsOffGrid]

@@OffGridGarageAustralia comparison to other roof eliminates ambient temperature.

[@antoni_sk]

Hi Andy, unfortunately, there is no other solution than to start measuring each panel. Then, if necessary, measure the voltage drops across the individual parts. It's weird that every string made up of different panels has the same problem. I keep my fingers crossed that you will find the problem quickly.

[@OffGridGarageAustralia]

You are correct. Thank you.

[@kevinmills5293]

Try hosing down the roof and panels. I’ve some pretty old panels and they don’t like the heat in summer.

[@AQUATICSLIVE]

I know we are probably on a delay on this but wanted to share something that happened to me. Something to check with low-performing panels check the Schottky diodes mine were making the panels lose some power well about 40% so not as bad as yours but confused me for quite a while. I just bought a big bag of Schottky diodes and replaced them all after finding one that was low resistance both ways.

[@gordonfoat8269]

You might have a hot-spot on one panel pulling the rest low, buy a thermal camera and you will see what's a good and what's bad and where the high resistance is 💪 A C2 flir will help. These thermal cameras are very economic nowadays 👍

[@OffGridGarageAustralia]

I tested the strings individually...

[@vickipps6821]

Maybe bad connections in the connection box on the panels due to the fact they are older panels

[@georgedemean2228]

Im pretty positive it is heat related (West roof hotter than East one) Ideal solar production is in the winter sunny days, the only problem is that winter has shorter days....

[@TheFonz01]

Junction box issue, voltage drop in the wiring from panel to charge controller. Check voltage drop from panel to charge controller

[@bobfoulke4875]

That's frustrating so I sent some foamy troubleshooting help. Best wishes on a quick easy resolution. Waiting for the next exciting episode of OGG

[@budmartin3344]

Can you try connecting 1 panel of each column in series to see what you will get for each row?

[@Gnagnie]

Are these the panels where the mc4 connectors were cut off?

[@andrewradford3953]

I used an old DC isolator with mc4 leads to create a short. Then check short circuit current on each string. Also test for earth faults by looking for volts from positive to panel frame. Keep halving your faulty string until you find the panel. Use a single mc4 extension lead that can run the length of the string. Don't do it on a 34° day! Especially without a hat when folically challenged.

[@OffGridGarageAustralia]

Do I need a tin-foil hat? 😂

[@neduodumbu1969]

Good job. To resolve the low power problem, I suggest you measure Voc and Isc per panel, and sort the panels to provide roughly equal Voc per string. Check the cables on panels with low Isc and change the panel if cable is good, or put such panels on a string of theirs, if the Voc is good.

[@johnhill3507]

interesting problem and video I am looking forward to you finding the cause and solution. your pain keeps us from suffer the same agony.. thanks for all your work on posting the video.

[@OffGridGarageAustralia]

Thank you very much, John!

[@petercamusojr1545]

I would look at the connection at the top of the garage ceiling. Where you combined the strings. That could be a hot spot. The 4 into 1 connecter was a friction fit.

[@harrymuurling2742]

I heard that to replace the diode in the older panels

[@teardowndan5364]

Since you are missing a whole panel worth of under-load voltage, you may have one bad panel per string.

[@Hstruik01]

If you have a infrared camera, check for individual hot cells, which could activate one of the bypass diodes reducing the power.

[@thomasmoore4576]

I've got the same problem with some of my panels I got four 100 watt new power panels brand new straight out of the box and I checked the diodes they're only putting out like two amps two and a half amps Max in full sun and it should be putting out five and a quarter with load without load it's somewhere around 6:00 and a half and they're supposed to be and on one side the diode reads 15 to 16 volts the other side reads about 7 volts I don't understand that because my other ones that I have it's equal on both sides and yes if the panels are too hot they will decrease I've got some 260 Watt and they put out an extra 150 w if I spray water on them and cool them down in the heating I look forward to the next video when you find out what it is maybe I can fix mine

[@lanceulbrich6249]

I had the same issue with one of my arrays I was certain the used panels I bought were junk. I tilted them a bit more toward the sun and they started producing full wattage. Is it possible your roof isn't perfect east west?

[@edwardvanhazendonk]

Can 1 panel have a shortcut, so bypass your strings to dedice which is causing havoc

[@OffGridGarageAustralia]

All strings have the same voltages, Voc as well as under load.

[@bloodcarver913]

Flipped some cables by error and parallelled them instead of series connection?

[@danhitchcock5913]

Your my #1 KZbin channel.. TRUE>.. Wacky Panels...I propose as panels pass current the resistance goes up in a individual panel group.. R=IE as you know.. Please calculate for resistance when powered with sun at a circuit location IN the panel circuit after an inside solar panel group and before its solar diode. Thunderstorms? or age? of the panel.. Thanks KZbin friend. These panels are not absorbing power perhaps and are just not providing power.

[@OffGridGarageAustralia]

Thank you Dan. More testing underway...

[@michaelkho79]

Can be the solar panel too long no used. Have to wait some time to recover the voltage and ampere ?

[@michaelgunzelmann1193]

It looks like a problem that effects all the panels equally. Wonder if some of the pass thru diodes are bad because of age? You seem to get only 2 panels of production even though there are 3 present. That leaves you back to your idea to check all the panels.

[@OffGridGarageAustralia]

Yep, seems there is no other way...

[@huskylfp1505]

Espero pronto saber qué fué lo que pasó! Muchas Gracias por compartir tus problemas!

[@feinedrachenrogerrumpel2126]

what happens, if you cool the panels down, using a garden hose?

[@mikenewman4078]

Andy, this is probably too late. To save pain when doing individual panel short circuit tests make up a test lead so you don't have to cut all your cable ties. Carefully note the polarity of current at each test. I have had a panel that failed one side which absorbed current. Voltage was down by half a panel value.

[@OffGridGarageAustralia]

I'll check this again. Thanks.

[@superpierrot]

Hello, « Mixing different panels, whether connected in series or in parallel, ALWAYS reduces the installed wattage. « & « In series, the total current is determined by the panel of the lowest current rating ». I can't post the source here - please google the first sentence to get the link ^^

[@uhjyuff2095]

The panels produce less when its hot outside. Spray the panels with your water hose to cool them off!

[@edwardvanhazendonk]

Hi Andy, what happens if you have only east or west, does it crawl up? Maybe the mptt is maxed out by the current?

[@OffGridGarageAustralia]

SCC is below 60% load, the second one below 30%.

[@claudioporto5926]

Check short circuit current for each panel if all looking good, , them measure each individual panel voltage with the all panels in a string connect to the charge controller you will find the weak panel in the string

[@davegeorge7094]

You must check voltage on each panel while in series and make sure MPPT is drawing MAX power by your calculations derived from panel max power voltage drop from open circuit voltage.

[@SuperVstech]

If you have an IR camera, you can look at the panels and see dead cells. Also powering them at night will show bad diodes by outputting light in the uv range...

[@ArthursHD]

Could try a thermal camera like HT 301 Too hot panels? There are combined solar thermal + solar PV panels 🐸Is out there :) Curious how it'll play out! Best of luck and dedication at fault finding! Thanks Andy for sharing! Thanks viewers for suggestions/comments!

[@digital-experiance2390]

Ok, watched it to the end. Not staged :-o To help: you put three strings in parallel on one charge controller? How do you think the mppt will work? Make the strings longer. Maybe all 6 in one string. Clean the panels! The leaves on the panels take at least 1/3 of the power away! This triggers a lot watching the video. Do not! disconnect under load. You will burn the connectors. Even at 2ah. If all 6 panels are in one string, they should have the same power and voltage, plus the sum of the voltage should be correct. Then you can look at the power.

[@henvern]

As others have said, it seems one panel in each string is connected in reverse polarity. Bypass diodes operating. One manufacturer may be putting their MC4 connectors on with opposite polarity to the other manufactures.

[@henvern]

Possibly can determine which panel is not producing by measuring panel temperatures. Hot one is not sending it’s power to your battery.

[@jmaus2k]

Voltage matches the high temp rating of the panels. It isn't a reversed panel.

[@edwardvanhazendonk]

Sorry to be spamming, can your mc4 or panel connection be corroded, you see voltage but current will not flow

[@OffGridGarageAustralia]

You're not spamming, Edward. Glad you have more ideas 😉 As in the previous video, I had to crimp some new MC4s onto the cables as they cut some connectors off. So at least these new ones should be good.

[@CyrilHarnisch]

Andy, you refer to the spec open circuit voltage, but I thought that voltage decreases as the panels age.

[@OffGridGarageAustralia]

It does but only a very small amount. After 10 years, they still should produce 97% of their initial power.

[@Raphael_Hofmann]

Voc and Vmpp is probably lower because of your high temperatures. It looks like you are ending up, shorting each cell and measure the current...I'm keen to see the difference between the new and old ones. Maybe you actually have only one bad panel per string and it is pulling down the others.

[@jasondevine6014]

Good job trouble shooting. As I watched I would say do such and such next and that is exactly what you did! I would put all odd panels on one string.

[@OffGridGarageAustralia]

Thanks Jason. That's what I did (tomorrow's video) 😉

[@RJ-cc1fz]

How long is your wire run from the panels, what gauge wire are you using for that run? It looks like it’s not thick enough Also it’s realistic to only expect 70% of the max new panels say they can produce. That’s with proper sized wires. Now if your panels are also used- 10 years old, you will get less than 70%.

[@SylwerDragon]

There is also possibility to load test them..I know it require load tester.. but those are not so expensive and they work pretty well for 200 -300W ..So you can test that too..it would be interesting thing to do..just to see real power coming from them and you don't have to test on those on your roof..test it on some that are on the gorund..or one of those new news you bought just recently :)

[@edwardvanhazendonk]

You do not see open voltage, but the voltage when you see load

[@JohnSmith-xn3fr]

Batteries full ?

[@OffGridGarageAustralia]

Less than 60%

[@Sylvan_dB]

I try to match the panels in a string. I'd be separating the panels and doing panel by panel troubleshooting. The age should be fine, unless they were treated very poorly (e.g. a concentrator) in their previous life. Do you have some extension cables to attach to all 9 panels to bring the connections down to ground level for testing? (I hate rooftop panels...) Did you perhaps get a batch of copper-clad aluminum (CCA) wire?

[@OffGridGarageAustralia]

Next video ;)

[@nigelcharles511]

As all 3 strings are the same I suspect that you might find that all individual panels are similarly equally low pointing to old secondhand panels reaching end of life. As new panels have been getting so much cheaper I decided to buy 325W panels. I bought two sets on eBay. One set was Panasonic @£100/panel and the other Longi @£90/panel. So far only the Panasonic ones are connected up but in bright sunshine in March at midday in the UK I am getting 10.9kw out of 11.75kw for 36 panels. At least with new it is fit and forget. With secondhand, they will be cheap but they might come back to haunt you. Having spent good money on the rest of the system I think that it is worth buying new panels now that the prices are so cheap.

[@OffGridGarageAustralia]

Yes, you might be right with that. I had a good run with the panels on the east roof and they have performed like new so far. And thank you very much for your many replies to other comments here. This saves me a lot of work commenting myself. You seem to understand the problem very well and can point people in the right direction which didn't watch all the videos or watched them only partly as they ask stuff which I clearly explained several times. So thank you for your assistance.

[@nigelcharles511]

@@OffGridGarageAustralia Very happy to provide input especially if it frees up more time for you to provide such interesting videos. Temporarily bypassing your PV to MPPT controller wiring should clear up where your problem lies. I hope that it is the wiring because it would be really bad luck if it was the panels. Normally you would expect a gradual drop in performance over time so less than 30% power output due to ageing is very unlikely. As you can get secondhand panels very cheap in your position I would have done the same. In my case I didn't have that option and the dramatic drop in the price of new panels got me started instead. Although I built my system last year, at that time cost effective LiFePo4 were not yet available so my current system uses 48kwh of fork lift truck batteries linked to Victron MPPT controllers and inverter. Your videos are a great help to me in planning my trailer based LiFePo4 system. This will be used to import power from my offsite PV system and in combination with a Kia EV6 (which I am told can export up to 3.6kw) I am hoping to locally produce nearly all of my electrical power requirements. It should work out OK most of the year but UK winters usually challenge panel output and require more battery storage. At a latitude of 50degN winter days result in much shorter charge times but the real problem is the is the significant periods of overcast conditions when there is so little solar power. You are very fortunate not to have that problem in Australia.

[@Aconda]

One comment for the algoritm. Will watch later. :)

[@OffGridGarageAustralia]

Thank you, hahaha

[@forresteralex]

I had a similar issue with my LG bifocal panels... but when I started to heavy pull from my lithium cells it kicked up in power of the panels... it could be your victron units trying to protect the cells??

[@OffGridGarageAustralia]

No, that's not the case. SCC don't protect cells. That's what the BMS is for. Battery was at 60% at the time of testing.

[@edwardvanhazendonk]

Measure the direction the power on the seperat strings, this will show if the are shorting another string. When 1 panel might be bad

[@glenb1356]

A couple things: I cannot do what you did, disconnect while the sun is shining. I did it once and it knocked me on my butt, presumably from static build up. Also, you must match the current in high voltage strings. You CAN connect an 8 amp panel with a 10 amp panel, but you will never see more than 8 amps out of the string. Voltage does not matter in serial strings, only amps. The best idea is to use an inverter or charger that has multiple string inputs, so you can use similar panels together on one string. I have two systems and three inverters. 8kw on a contract (separate meter) with Georgia Power Company, and 6kw grid tied. I am using two Fronius inverters on the GA Power, and an SMA 7kw inverter on the grid tie.

[@jamest.5001]

I would test the panels individually, if they are different, match in groups best as possible, so all parallel groups are equal as possible,

[@BastelPichi]

Connect a small mppt to it so you can see the max power point individully

[@OffGridGarageAustralia]

That is in tomorrows episode.

[@RemScanProducts]

I'm guessing a corroded connector. High resistance path. Look for a melted MC 4.

[@offgridwanabe]

Hate to say it those bypass diodes maybe poor connection looks like you need to do it one panel at a time, also what kind of connectors are you using I certainly can't get mine apart that easily. Maybe that is why they were free lol

[@BajanAlan]

I thought he had taken them apart off camera then loosly put them together!

[@davegeorge7094]

Yes. too easy. I see they are a different design of M4. Those 2 barbs hang on even when depressed firmly, I made custom reverse pliers to pull them. His have a butterfly that depresses the barbs, looks like.

[@lucvanhoeylandt8649]

I would guess temperature would account for some of the losses (depends on the internal temp of the panels). It's also normal that the MPP voltage during your testing will be lower than the MPP point on the label of the panels (those are the values measured at 25 degrees), higher temp = lower voltage, lower temp = higher voltage. Also combining different types of panels with different Impp will cause less yield (you only showed the suntech labels), are the Impp's the same ?

[@leonclose7823]

Could it just be one MC4 connector in each string has high resistance? Unlikely in both strings, but you've ruled out all the likely problems so it must be something unlikely.

[@OffGridGarageAustralia]

Yes, that could be the case. I'll check them again. I have replaced some but not all.

[@WickedIllusion1]

I'm thinking the wire going from the inside ceiling junction box to the MPPT controller is too small for those 9 panels (3 strings) and has high resistance and limiting the amount of current that is flowing. Maybe? I forget what size mm wire you used... and remember to calculate the length of the cable into the equation...

[@OffGridGarageAustralia]

I tested the strings individually with no improvement. If you theory would be right, I would see a different (better) result with only one string. Also, I use the same 4mm (~11AWG) cable for the east side and they work fine.

[@defjamsgreen]

HOW MUCH VOLTAGE EACH PV MODULES ARE PUTTING OUT BY TRYING A VOLTMETER AND COMPARE WITH THE OTHERS AND THE CHARGE CONTROLLERS INPUT VOLTAGE WHILE YOU HAVE SUNLIGHT . ONE OR SOME MAY BE VARYING BY AGE AND WIRE FATIGUE .

[@notyoung]

A solar panel's RATED (label value) output is measured under STC (Standard Test Conditions) which are typically only found in the factory, including the panel being at 20C. A more realistic power rating is the NOCT (Nominal Operating Cell Temperature) rating which is about 73% of the STC rating. The actual ouput of a given panel can be anywhere between those two values. Most of the "100 Watt" panels I've tested only reach 75-76% of STC at my location. Some "250 Watt" Jinko panels reached 235 watts (94% of STC) under the same backyard testing conditions. Care to guess which brand of panels I trust? All my solar design spreadsheets use NOCT values so you won't be disappointed when the batteries go empty because there wasn't enough solar power to handle the loads you planned. Doing the math, the most power I would expect from your 1.3KW and 1.7KW arrays would be: 1.3KW * 0.73 = 0.949KW 1.7KW * 0.73 = 1.241KW Panels lose power output when hot and you've talked about the temperatures there being 30C and up. Black solar panels in the sun will be appreciably hotter than the ambient temperature and will thus have less than the STC power output. The panel label you showed had a NOCT of 45C. Measure the actual temperature of the cells and see how hot they are (the basic IR thermometer for $30 or so is probably adequate). If the cells are above 45C, then they won't produce even that level of power. ONE bad panel in a series group could bring down the power output of that string. My first suggestion would be the per-panel testing you are doing, but I would have done that before mounting the panels on the roof. Nothing fancy, just measure the Voc and the Isc of each panel under similar illumination - whether new or used panels.

[@chrislewis3247]

Are you get one more controller an put 3 panels on it in series

[@petercamusojr1545]

I reviewed this video again. My take away. 1. String 1 has 3 panels by the same manufacturer. 2. String 2 has different manufacturers, 2 old panels and 1 new panel 3. String 3 has 1 panel that was suspect panel from your house. 4. Every test I saw always had string 2 in parallel with other strings. Recommendation.. Try to get string 1 working to expectations all by itself. String 1 is the only one with 3 panels of same manufacturer and age. Do not mess with string 2 or 3 until string works.

[@GeevyLic]

Andy sometimes we just need to step away and it will come to you. I would first check the series wiring, each end of the wire is the opposite. Male female right? Then I would check the mc4 connector I have found too small of the male to the female yes I know common problem in life .I always butt connect or twist with wire nut just to figure out the problem.

[@yodab.at1746]

Get a hose pipe and cool the panels down to see if current goes up by much

[@OffGridGarageAustralia]

Not that hot under these conditions.

[@vaneay]

Some bypass diodes are damaged ?

[@Gnagnie]

check your clamps inside the garage. at 11:45 you show on it!

[@walterweese2527]

if this isn't the isue check your cabeling (MC4-Connectors to junktionbox of the solarpanel, next check the bypassdiodes) but still guessing hmmmmmm edit: now I know: They behave like humans, they have burnout-syndrom. yes i belief. ;o) edit2: Prost Andy :D

[@bishwagit]

I have 4 100w new Pannel connected in series. But only getting 130w max in peak. Can anyone help me, why?

[@chiefkeith5641]

If those random two panels on the opposite side of the roof are connected to those panels and it’s a string circuit that’s your problem

[@vicamaral]

Corroded cabling in back were cable junction box maybe Diodes