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Bad panel- testing/repair/how to dispose of?

Ryujin

Solar Enthusiast
Joined
Feb 28, 2023
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592
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US
Once again thanks for all your help.
I believe it was Sunshine Eggo who posted something somewhere about using some cardboard to test your panels.

I have two almost exact set ups, both on five 270 Watt panels (1350 potential watts), over paneling a 40A charge controller. I noticed consistently when both systems were low enough to have the charge controllers use the MPPT, one systems charging was 80% lower than the other. So I put together some duct tape and card board and went about testing each panel with each system on a 1900W load in full sun, and sure enough the system that was consistently 80% lower had one panel that didn't seem to effect the Amps as shown by the charge controller.

I disconnected it, tested the VoC and it seemed in par with the others (39V or so). However, when testing the VoC with either of the + or - cables connected to the rest of the panels, the VoC was 5 V.

My multi-meter is only rated to 5 amps, so I haven't done and Isc tests. Is there any other tests you can suggest doing? Would it be worth looking into the panels fuse box? Any repair suggestions welcome, I know panels aren't expensive but I don't have that much money and have lots of time. Maybe I can use it for the small 12 V PWM controller and 3 year old neglected Marine/RV battery system I have for our (non well) water pump.

Besides the dump, if this panel doesn't work how would you suggest disposing of it?

Thanks for any input!
 
P.S., maybe a dumb question but I'm not sure so I'm asking, if I'm calculating the watts being delivered from my panels using my SCC's amps, do I use the voltage the SCC shows the panels (30-36), or do I use the voltage the SCC is charging the system at (27-29.2)?
 
P.P.S., would leaving this bad panel connected lower the efficiency of the rest of the system? Its about to rain so I didn't want to leave connections open.
(edit all in parallel so I don't think it would)
 

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