Solar panel produces volts but no amps??

howzdishowzdis Registered Users Posts: 1
Hi iam new here but this seems like a knowledgeable community with plenty of good people and info.

The problem iam having is like the title describes I have a folding 240w solar panel that is practicality new it's a 12v panel converted to 24v by series wiring 1 positive and negative wire together. However when I connect it to my system my chargers ( morningstar ts-60s) stop getting amps all together until I disconnect it then everything returns to normal and I'm back to getting between 60 and 75 amps depending on the day and sun and shade etc.

After getting it back down off the roof and putting out in the yard with good sunlight and getting my multimeter I find when I test the output on the panel with the grey Anderson plug it is producing around the same amount of volts as the rest of my panels which fluctuates between 18 to 21 volts.

So I'm not quite sure what the problem is as once I remove it from the system everything is fine again. Any info from anyone that has had similar problems and experiences would be appreciated. I'm really hoping there's a not overly hard or complicated way to fix this as it's still a new panel.

P.s wasn't sure where to post this so moderators please feel free to move this thread if need be.


  • PhotowhitPhotowhit Solar Expert Posts: 5,225 ✭✭✭✭
    Re: Solar panel produces volts but no amps??

    Does it have amps across the leads with out connecting to your system?

    How/who determined that the rewiring was done correctly? 18-21 volts across the leads would be roughly correct if wired for 12 volt charging.

    So your connecting this to an existing system, which I infer is a 24v nominal system? Which has 2 TS60's and you went from producing 60-75 amps to nothing? Sounds like it was shorting out the 2 charge controllers, did you have some type of fuse or breaker when you installed?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do
  • BB.BB. Super Moderators, Administrators Posts: 30,646 admin
    Re: Solar panel produces volts but no amps??

    It sounds like you have wired the new panels "backwards" to the rest of the array. Solar panels wired backwards (+ to - vs + to + parallel connections) act like a dead short (solar panels are just a bunch of giant diodes==Connect them in the wrong polarity, the panels will simply be a large set of diodes connected backwards and take current from the rest of the array).

    Note that while solar panels are pretty rugged, if you you connect them backwards, it is very easy to smoke the array with too much current. 60-75 amps through a single (or pair) of small panels is ~10x their normal Isc rating).

    Also, if you have three or more parallel strings of panels connected in parallel, you should have a series fuse/breaker (typically called a "combiner box" with multiple breakers/fuses inside) per string to prevent short circuits from starting a fire.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Solar panel produces volts but no amps??

    Some prefabricated interconnect cable sets are wired in a non-standard way and matching colors of the MC4 connectors will cause the panel to be wired in backwards. Is it also possible that while rewiring your folding panel to a series connection you mixed up the + and - leads for the set.
    SMA SB 3000, old BP panels.
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