Problem with solar panels or wiring

Hi. I have three Kyocera 120-watt solar panels on the roof of my RV. They were professionally installed and wired. Two panels are on one set of wires, while the third is on another set. My controller is a Solar Boost 2000E. The lone panel on one set of wires appears to be functioning well, while the other two panels aren't. I can cover the two panels with towels and my amp reading drops a little (2-3amps in full sunlight), while covering the other panel drops the amps by 6 or 7 amps.

I have a good VOM. Could someone tell me what the volt readings should be at my controller from the two-panel wire, and what the volt readings should be at the terminals of each panel. I suspect I have a loose wire somewhere, but I need to know how to isolate it. Oh, I'm picking volt readings instead of current because I don't have to disconnect anything to measure voltage (I think).

I'd appreciate comments, trouble-shooting tips, etc. Thanks.



  • BB.BB. Super Moderators, Administrators Posts: 28,315 admin
    Re: Problem with solar panels or wiring

    It looks like the Kyocera KC120-1's are rated:

    Module: Kyocera KC120-1
    Max Power Voltage - Vmp 16.9 Vdc
    Open Circuit Voltage - Voc 21.5 Vdc
    Voltage Temp Coeff - Vtoc -0.0824 V/°C
    STC Rating - Pmp 120 Wstcdc
    Max Power Current - Imp 7.1 Adc
    PTC Rating 105.7 Wptc

    Simple test to see if panels are OK... First disconnect all panels from each other and measure their Open Circuit Voltages, depending on temperatures, the open circuit should be around 21.5 VDC or a bit less.

    Next, set the meter to 10 amps full scale and place on each panel--again the short circuit current should be 7.1 amps, or a bit less (up to 20-30% depending on age, temperature and dusty-ness is OK)...

    If the panels are OK, then you will have to debug the controller and its connections.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Problem with solar panels or wiring

    Thanks for the prompt reply, Bill. I'll wait for the cool of the morning before clambering up on the roof and working. Standard southern AZ weather....

  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Problem with solar panels or wiring

    the kc120 working current is 7.1amps, but the short circuit current is higher than this.
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