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Bill-R's avatar
Bill-R
Explorer
Mar 03, 2015

solar panel output

I bought a used 36 ft mh. It has 2 18x40" solar panels and one 12x22" solar panel and I am wondering how many watts it will put out. Ball park estimate. It is charging 15 volts during bright sun. It is charging 4 deep cycle golf cart batteries that I installed last week. I have no information on this set up and the company that made the parts is out of business. I am just curious as to the possible out put of the panels.

9 Replies

  • on page 15 that is a picture of my controller but it has no numbers on it the wiring and the connectors are rated for 30 amp, that is stamped on the connectors. I think it is the 9 amp version because of the wiring
  • Bill,

    A digital multimeter will give you a good idea.

    On a sunny day, at noon, check open circuit voltage at a panel's outputs, while disconnected from the controller. Then reconnect. Subtract a few volts from that, to get panel's approx. operating voltage, and times that voltage by the amps being passed thru to a depleted battery, for approx. wattage.

    That will tell you approx. panel Voc, Vop, Isc, and therefore approx. wattage.(all less than actual, seeing as it's still winter).
  • Solar prices continue to drop like a rock!
    Looking forward to more posts on this subject.
    I'm thinking about 4 Hi voltage panels on our coach, just need to get a mockup cut out of carboard so I an go up on that roof & figure out how many panels I can put up their. Hi voltage panels down to a $1/watt
  • I have a pair of 45 watt panels that are about the same size as the larger ones that you described.

    I installed a pair of 120 watt panels back in 1999, and they cost $429! Now you can buy a 120 watt for about $175 each. SunElec.com

    As long as they are working, I would leave them up there. They will keep the battery full while in storage, yet when camping, the CO, Propane detectors and refrigerator combined will use about 35 amp hours daily, or about what all three panels will produce.

    So you will need to shut off the propane detector and refrigerator while in storage to keep the battery full.

    There are several posts on how people have changed to LED lights if you are interested. I used some LED panels with 24 each 5050 LEDs on one panel. It is fairly bright, and draws only about 1/4 amp each.

    Have fun camping!

    Fred.
  • What is a PBR controller? I'd think long and hard about putting any $ into the controller.

    Can can you see under the panels and read the make and model with a mirror?
  • smkettner the controller is a PBR controller with two adjustments on the face.
    MrWizard I dont know the age of the panels. The panels are not bolted to the mounting brackets, the are screwed in with sheetmetal screws. I am looking for some more info on them, found the original engineer of the maker and am trying to run down some more info. I am planning to update the controller with a digital read out one.
  • you didn't say how old they looked to be
    but i'm guessing

    the two 18*40 are about 50w each
    the 12*22 is likely 15~20watts

    if you undo the side bolts and tilt the panels
    the pt# and power info will be on the back side of the panels
  • I am guessing 180 to 200 watts total. Should serve you well.

    What controller is it? 15 volts is maybe on the high side of normal depending on use and conditions.

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