My Off Grid Cabin Is Down!

Came back to our off grid cabin after a month and found that the solar system was not producing anything. Found the 100 amp breaker popped. Tried to reset but it wouldn't reset. It appears to be bad because it wont reset even with the wires removed. Next I checked the power coming in from the panels. 62 volts! What the heck. I have three 12 volt panels tied together and they have been giving me 36+ volts for years now. I tested the continuity of the feed line from the panels to the Morningstar TS-MPPT-45 controller and it is good. I then tested each solar panel and each of them was producing just over 20 volts each which is at the open circuit voltage according to the info plate on the panels.

Can someone shed some light on what has happened to my solar panels?. [h=2][/h]


  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    Just where in the system is the 100 amp breaker; between PV and CC? Between batteries and inverter?

    If between PV and CC then maybe there was a lightning hit. That can fry a breaker.

    You have the Voc reading of 62 volts as the panels are in series, or so it seems. That is natural when the current from the panels is going nowhere, an open circuit.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • The Grand Pooh-BahThe Grand Pooh-Bah Registered Users Posts: 3
    Breaker is between panels and controller.
  • BB.BB. Super Moderators, Administrators Posts: 30,184 admin
    Since you have a Morning TS MPPT charge controller--Three panels in series for Voc~63 volts or so is perfectly normal if there is no charging taking place (if the controller is charging at full power--The Vmp-array should be around ~54 volts or 10-20% less (hotter the panels, the lower Vmp-array will be).

    As Don asks, how is your DC battery bus organized (breaker size to what devices). Typically you would have a breaker to the TS 45 controller (x1.25 NEC derating would be ~60 amps) from the battery bus. And another breaker to the AC inverter (sounds like a 600-1,000 Watt AC inverter on a 12 volt system?). Etc. Another breaker/fuse to a DC water pump and such.

    You should not have a single breaker (charge controller, inverter, other DC loads) all connected to all DC devices... A single failure can "turn off everything"--Including your charge controller.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • The Grand Pooh-BahThe Grand Pooh-Bah Registered Users Posts: 3
    System is 100% 12 volt. Kitchen and bathroom Fan, lights, furnace, TV, radios, ect run on 12v. I'm going to take the laptop and plug into the Morningstar and see what it says is going on.
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