Solarex solar panels

Mike M
Mike M Registered Users Posts: 11
I have two Solarex Millennia panels to play with. I'd like to build a small system to run some LED yard lights and have a small battery back up in the case of a power outage. The yard lights haven't been spec'd yet but I build my own DC circuit and the LED's run at 500ma - 1000ma.

My panels were part of a larger system that was on a house. They were a cheap Criagslist deal and picked them up for $20. There is a red and grey wire on two of the four corners. Each panel puts out 84 volts.

I hooked up the wires, red to grey and checked the voltage at each corner and then from a red on one corner and a grey from the other corner. I still got 84 volts. I hooked up the panels red to red and grey to grey, checked the voltage from several spots and still got 84 volts. Should I be getting more than 84 volts with them hooked together?

Once I figure out what I've got I plan to sit down and see what I want to light up and how much power I'll need and battery size. I assume this will determine if I wire the panels in series or parallel. (?)

I've done a smaller LED system with a 10w panel and short runs of wire. My system will be a little higher demand, hence the want for a larger panel, and wire runs a bit longer. Should I leave my long run of wire, ~50', between the panels and the charge controller? Or the controller and the battery?

Pictures:
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Before cleaning them.
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Comments

  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Re: Solarex solar panels

    You need to figure out the wiring on the backside of the panels. Should only have a one positive and one negative wire per panel.
    Secondly need to clean panels and Voc voltage will come up.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solarex solar panels

    Are you planning on running them behind a MPPT charge controller?

    That high Voc would only make sense using an MPPT charge controller or using a PWM controller on a ~48-60 VDC battery bank.

    If you try to use them on a 12 volt battery bank with a PWM controller--You will get very little wattage out of them.

    A maximum of ~0.6 amps Imp... Or around 0.6 amps * 15 volts = 8 Watts useful (using a PWM charge controller).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Mike M
    Mike M Registered Users Posts: 11
    Re: Solarex solar panels

    Thanks for the replies.

    One of the photos above shows the stickers on the back of the panel. There isn't anything in regards to wiring. Googling the panels and part numbers doesn't turn up much useful.

    From what I've been reading an MPPT controller is the way to go so yes. The plan so far is a 12v battery, yet to be determined.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solarex solar panels

    How cold does it get in your area? You might need a "full sized" MPPT charge controller with a minimum Vpanel-in >100 VDC... Which is the Midnite, Outback, Schneider/Xantrex, etc...

    None of those are very cheap charge controllers (around $500 minimum)--Which begs the issue of cost of your panels+high end charge controller and "a few inexpensive used panels" vs just getting standard 12 volt panels + PWM or GT solar panels and a medium to high end MPPT charge controller...

    Before you buy anything else, do some paper designs and work out the costs+benefit issues.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Mike M
    Mike M Registered Users Posts: 11
    Re: Solarex solar panels
    BB. wrote: »
    How cold does it get in your area? You might need a "full sized" MPPT charge controller with a minimum Vpanel-in >100 VDC... Which is the Midnite, Outback, Schneider/Xantrex, etc...

    None of those are very cheap charge controllers (around $500 minimum)--Which begs the issue of cost of your panels+high end charge controller and "a few inexpensive used panels" vs just getting standard 12 volt panels + PWM or GT solar panels and a medium to high end MPPT charge controller...

    Before you buy anything else, do some paper designs and work out the costs+benefit issues.

    -Bill

    Interesting. You're exposing me to new territory which is great. I didn't realize there was so much more to handle with higher output panels. I got the panels because they were cheap and in the end my LED array won't be too demanding. As such I don't think I'll be discharging the battery too much so using the panels to their full ability might not be necessary. Maybe a smaller MPPT controller would work. This is just a back of the envelope project.

    In the end I'd like my ~2 amp LED lights to stay on through the night, everynight and the battery to be charged during the day. I'm near Sacramento so it doesn't get "cold" although we do have freezes.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solarex solar panels

    There are very few (if any) "small/inexpensive MPPT" controllers that have over a ~70-100VDC solar panel input.

    Rogue has a 100 VDC maximum input MPPT controller. Marc makes a very nice controller and includes many items that other companies charge arms and legs for. Still not "cheap" by any means. And it is close if 100 VDC limit will work with these panels (Voc-cold, panel voltage rises with cold weather).

    Midnite is coming out with a new/smaller MPPT controller--Perhaps it will work too...

    This is why we suggest doing paper designs first. There are a lot of hardware combinations that do not work well together (either functionally, or just "too expensive" a solution).

    Your "cheapest" solution would be to put a bunch of LED's in series (get operating voltage higher and use a ballast resistor to control current--unless you want to go down the road of a current mode digital switching power supply as a ballast).

    Otherwise, get a "12 volt panel" (Vmp~17.5 volts) and a "cheap" PWM solar charge controller.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Re: Solarex solar panels

    Temps for cold nights have been in the lower Teens, Chico has seen record lows at 11 degF . Remember back to 1990 when water pipes burst from freezing all over the valley?

    as stated on what you would need to use those panels you could buy a 250 W single panel and pick up a low cost MPPT controller and be far ahead on useful power.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!