Forum Discussion

Fishbreath's avatar
Fishbreath
Explorer II
Apr 26, 2014

Bad Solar Panel/Symptom

My friend had the roof on his 5th wheel replaced last fall. He noted that the single solar panel on the roof no longer worked after being re-installed. I checked the panel output and it would momentarily show about 16 volts and then go immediately to zero. Is this the symptom of a shorted panel?
The panel is about 15 years old: Unisolar 64 watt, 3.88 watt, 16.5 volt.
This panel is used to supplement a portable 100 watt panel and has met his needs up until now.
If it needs to be replaced (most likely) I would like recommendations on a replacement panel and vendor that has been satisfactory.

Thanks for any suggestions

Bill
  • AlbertaNewbie's avatar
    AlbertaNewbie
    Explorer
    Apr 27, 2014
    If you are in Canada id recommend solarwholesaler.ca. best prices in Canada that I could find
  • DSchmidt_2000's avatar
    DSchmidt_2000
    Explorer
    Apr 27, 2014
    Sounds like there is an intermittent connection that when 'broken' is either completely broken or is high resistance.

    I had a small 10W panel from Ebay that did this. Ended up being a bad solder tab between the cells. Would sometimes make a connection, but put a heavy load and it would open up. DMM's have such a high input impedance you can get a good reading but there's not current behind it.
  • westend's avatar
    westend
    Explorer
    Apr 27, 2014
    Maybe bad diodes? Those Unisolar, at least the thin film ones, have everything encapsulated, right? I've no idea what Unisolar built 15 years ago.
  • Fishbreath's avatar
    Fishbreath
    Explorer II
    Apr 27, 2014
    Sorry, I should have been more specific.
    I did remove the panel. I get the surge/then zero reading with the panel on the ground in direct sunlight with no load. I took the readings from the wires that come directly from the panel.

    Hope this helps, but I do think the panel is bad.

    Any recommendations on a vendor that you like would also be appreciated.

    Thanks
    Bill
  • BFL13's avatar
    BFL13
    Explorer II
    Apr 26, 2014
    Remove the panel and check the junction box at the back, looking for a loose wire at a terminal. Perhaps when you measured it, the wire got to touch and then wasn't touching after that. The roof guys may have done a poor job putting the panel back on.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Apr 26, 2014
    Check the amps: 0V and 3.8A means a short in the wiring external to the panel. 0V and 0A means bad panel.
  • 2oldman's avatar
    2oldman
    Explorer II
    Apr 26, 2014
    Fishbreath wrote:
    If it needs to be replaced (most likely)
    I had a panel short out and leave a burned spot on the back. Check for that.
  • doughere's avatar
    doughere
    Explorer
    Apr 26, 2014
    If it worked before, and now doesn't work, sounds like it was not rewired correctly. I'd disconnect panel and check output; if a steady voltage out, start tracing wiring back to controller, then output to battery.

    I can't think of what else would cause the bouncing output you're describing (there are plenty of other things I can't think of so that doesn't mean much).

    Doug

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