Solar panels underperforming.

[ems437]

I have three of the 190 watt GoPower panels connected to a GoPower 30 amp MPPT RV-C controller. I noticed that I was only getting about 3 amps total.

I contacted GoPower support for some input and they had me disconnect the panels and measure the voltage and current individually directly from the panel leads.

Sure enough each panel is generating about 22volts and 1 amp or less current. It seems really odd to me that all three individual panels would drop their current output to something similar at the same time, in the same way. So GoPower is sending me three replacement panels under warranty.

My question is what would have happened to all three panels at the same time? I didn’t open up the connector box on the back of the panel and measure across the diodes yet since GoPower said the readings are all low so they are replacing them under warranty.

I’ve tried disconnecting and covering the panels to reset them. There isn’t really much more that I can think of that might make these three panels come back to life with full output again. Could bad diodes be a possibility that would
Make panels put out about 1/10th of their potential capacity? Does it warrant opening up the box on the back of the panel and measuring across the diodes? Or are the diodes not a likely culprit? Any other thoughts or ideas?

Any input appreciated.

Thanks!

[ARoamer]

Likely poor / failed connections between the cells inside the panels.
Odd that all 3 failed the same way, but possibly a bad batch?
For $447 each retail it's a good thing you have a warranty!

"The Go Power! GP-PV-190M solar module is built to last and features a 25-year limited power output warranty"

[Kevin Cooper]

Those panels are configured for 12 volt output. Each cell is .5-.6 volts. Two rows of cells are connected in series, and the two series connected strings are connected in parallel when correct. So, if you are getting 22 volts, it is because the two parallel connection is a series connection and all cells are in one series string.
How long have you had them? Did you test them for voltage when they were installed? If they weren’t checked before, I’m guessing they came that way since it’s all three. I suggest checking voltage before installing the replacements.

[ems437]

Originally Posted by Kevin Cooper

Those panels are configured for 12 volt output. Each cell is .5-.6 volts. Two rows of cells are connected in series, and the two series connected strings are connected in parallel when correct. So, if you are getting 22 volts, it is because the two parallel connection is a series connection and all cells are in one series string.
How long have you had them? Did you test them for voltage when they were installed? If they weren’t checked before, I’m guessing they came that way since it’s all three. I suggest checking voltage before installing the replacements.

It’s a 2023 trailer and I just got it in April. One panel was factory included and I added the other two at the time I bought it. All three panels were manufactured in 2022 with serial numbers that are close together, and were new to me about four months ago.

Your thought process is better than anything I’ve been able to come up with so far. When the new panels get here, I’ll definitely be checking the voltages and current before I plug them in on the roof. Thanks for the idea!

[Kevin Cooper]

Not sure how you are checking current, but the voltage is the important check.
Is your Go Power controller the Bluetooth version? Did you get the app if it is?

[ARoamer]

Originally Posted by Kevin Cooper

Those panels are configured for 12 volt output.

I believe your statement is incorrect, or I'm looking at the wrong panel's specs....

GP-PV-190M Solar Module specs-
Maximum power voltage (Vmp) 20.4V
Open circuit voltage (Voc) 24.09V

[pconroy]

Originally Posted by ems437

Sure enough each panel is generating about 22volts and 1 amp or less current.

If you just plugged your voltmeter into the leads coming off the panel, full sun, no shade, no load then I think what you measured is called "Open Circuit Voltage" and 22V is fine.

Typical Voc's are 21ish volts for a 100watt 12V panel. As for the current, that needs a "load" to measure it, doesn't it???

So I'm not sure that's indicative of anything. But GoPower would know for sure and if they're sending you replacement panels, I'd be curious to see what the new panels do.


I have "200 watts" up top and I typically see about 30-40 watts going to the battery. But, I've always figured that's because my "needs" are usually low. The house battery is usually charged, we're often plugged in, etc.

Yeah - 100 watt panels usually deliver a fraction of that but still...


IOW, my MPPT controller knows I don't need that much current. The excess wattage produced by the panels is going to the heat-sink.

[pconroy]

Originally Posted by ARoamer

I believe your statement is incorrect, or I'm looking at the wrong panel's specs....

GP-PV-190M Solar Module specs-
Maximum power voltage (Vmp) 20.4V
Open circuit voltage (Voc) 24.09V

You're right... Hmmm.


I typically see 15-18V coming off my "12V" panels. I've never measured Voc. This is 15-18V when connected, but before the MPPT.

[Kevin Cooper]

I believe you are correct! Somehow I got to the wrong spec sheet! Thanks for telling everyone.
So, the 22 volts was correct.

[ems437]

Originally Posted by Kevin Cooper

Not sure how you are checking current, but the voltage is the important check.
Is your Go Power controller the Bluetooth version? Did you get the app if it is?

I measured open circuit voltage directly at the panel leads in mid day direct sun with my multimeter on DC.

And then measured short circuit current by connecting the panel leads together and measuring with my DC current clamp meter.

Yes, I do have the Bluetooth remote for the MPPT controller and am able to read the input voltage and current to the controller from the panels on it. That’s where I first noticed I was only getting three amps PV input from the panels.

[Kevin Cooper]

Best wishes with the new ones!

[Spower]

Isn't 570 watts of solar panels a bit high for a 30 amp controller?? (asking for a friend )

[ems437]

Originally Posted by Spower

Isn't 570 watts of solar panels a bit high for a 30 amp controller?? (asking for a friend )

I think it depends on the panels and controller being used. The brand of panels and controller on mine are both GoPower and GoPower support told me to go with this configuration because they are sized to work together. The panels each produce about 9.3 amps in direct sunlight when measured with my multimeter. And with three of them, I’m generating 27.9 amps going to the controller, which is rated to run at 30 amps.

So I feel like they are almost perfectly sized for each other. GoPower just recently upgraded the rating on this line of 190 watt panels to 200 watts. I’m assuming the new model of this panel now probably produces right at 10 amps continuous in direct sunlight. Which would make 3 of them be exactly sized to feed the 30 amp MPPT controller exactly 30 amps continuous with this size of panels.

The controller itself has a max peak current rating of 100 amps max, and each panel is internally fused for 15 amps max, according to their documentation. So I think GoPower builds in some safety margin in what they can handle in case it gets a power surge.

At least that’s all my opinion in what I have learned with this build process on my system…. :-)

[ems437]

And just an update to this thread. I received the three replacement panels that GoPower sent me and swapped them out. All three panels are now producing what they are supposed to again.

So I did have three panels all go bad at the same time. I still have not been able to identify exactly what made all three of them stop generating their max output at the same time. But GoPower support wasn’t worried about it and said sometimes things go wrong. They said the panels are pretty straightforward and solid, so that’s why they have a 25 year warranty like this when something does go wrong.

I have to say I’m really impressed at their support and how well they stand behind their products. This was a really easy experience with their tech support and customer service departments and getting the panels diagnosed/replaced. So, even though their equipment is probably more expensive than most others, GoPower gets a solid positive recommendation from me if anyone decides to go with GoPower equipment.

[Bengalcats1958]

Anybody have an easy way to unplug the panel wires from the connectors on the roof after I cover the panel to prevent load while unplugging? I need to use a vom to test my panels but can’t seem the get them unplugged. I don’t want to damage the plugs.

[ems437]

Originally Posted by Bengalcats1958

Anybody have an easy way to unplug the panel wires from the connectors on the roof after I cover the panel to prevent load while unplugging? I need to use a vom to test my panels but can’t seem the get them unplugged. I don’t want to damage the plugs.

I got a set of these from Amazon. Less than $5 and next day delivery. The little tabs fit in the connectors and take them right apart. Works like a champ. I also used a pair of really small needle nose pliers before I got these. But these are way easier if you can wait a day for Amazon to get them to you.

https://www.amazon.com/Connectors-Co...s%2C110&sr=8-3

[ARoamer]

Originally Posted by Spower
Isn't 570 watts of solar panels a bit high for a 30 amp controller?? (asking for a friend )

Originally Posted by ems437

I think it depends on the panels and controller being used.

X2. Best thing to do is read your controller's specs and follow them, but usually it's higher voltages that might cause problems.
A cheap PWM controller is basically a switch that turns on and off super fast to regulate power to the batteries, too many amps may cause it to overheat, and overvoltage can destroy components.
MPPT controllers function differently, and some will simply ignore extra solar amperage, but will shut down if over voltage is detected.