Recycling Arco panels for a battery charger

706jim Solar Expert Posts: 516 ✭✭✭✭
My initial foray into solar power dates back to 1994. I purchased 7 Arco panels (about 1' x 4') five of them "Bronze" and two of them "Gold". These were salvaged from a solar farm in Arizona (I was told) and are brown in colour. 7 of these in series give an open circuit voltage of about 42-44 and they used to deliver around 5-7 amps when charging through an old AMPS on/off charge controller.
The rating for this group was about 170 watts. I am thinking of using these as a battery maintainer for my boat since they contribute very little to my present array.

So the question to the group is this: How many of these should I use to avoid overloading a simple PWM controller that would be charging two group 31 12 volt batteries in parallel?

Would it damage in inexpensive controller (none purchased yet) if I fed the whole 42 volts into it?

Or would it be preferable to use about four of them in series (they're about 6 volts VOC)?

And for nostalgia's sake, this group was about $700 USD back in 1974!
Island cottage solar system with 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 30th year.


  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,064 ✭✭✭✭✭
    Series 3 at a time for a 12 volt battery and PWM controller So you can go3s2p. or all 6 in series with a true MPPT controller. Beware of the cheap controllers labeled MPPT, they're not MPPT. 

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.