Wiring Solar Panel?

cswaite
cswaite Solar Expert Posts: 46
Ok, I just got a 130W solar panel yesterday and it has a Junction Box on back where you wire directly to a screwdown inside.

With panel facing down and junction box facing up towards me I figured Positive would be on left and Negative on right.

So, I wired it thinking Positive was on the left but I called the maker and they said it was on the right. Is this common to have the Positive on the right side?

The charge controller shows 0 Charge and the Charge light is very dim. Could this be a cause for this?

Thanks, im ignorant, but trying to learn.

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Wiring Solar Panel?

    Actually, I have looked for junction box wiring specification for several vendors (just two days ago for BP solar)--and I have never found a document that does a decent description of the junction box connections (series, parallel, diodes, +/- etc.).

    In the end, you will need to get yourself a volt meter (or an inexpensive DMM--I am still using mine from college almost 40 years ago) and verify all connections.

    You have to be very careful because connecting a solar panel to a battery directly, with reverse connections, can take out the blocking diodes or completely destroy the panel in a non-repairable manner.

    You probably are OK in this case because you have the charge controller in the middle between the panel and the battery bank. Reverse connecting the panel (if that is what you did) may or may not damage the charge controller (some are protected against reverse connections, others are not).

    Basically, disconnect your solar panel. Verify the output voltage (should be 18-22 volts or so in full sun). And, change your DMM to 10 amp current scale (also, you probably need to move to a different connector location on the face of the meter to measure high current) and measure the panels Isc (short circuit current). You should see:

    130 watts / 17 volts = 7.6 amps or so in full sun (or even a bit more).

    It is possible that you have tapped another voltage in the solar panel (6-10 volts) and/or are using only part of the array.

    Some panels are sectioned into two or more independent electrical solar arrays internally, and you have to connect each array together with jumpers to get the correct voltage/current output (most common would be to connect the circuits in series--just like the 3 D Cells in a flashlight).

    If you are unsure--contact the retailer or mfg. for details on the panel box connections.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    Re: Wiring Solar Panel?

    Without knowing which brand and model of panel you have, it is pretty difficult to give a good answer.
  • cswaite
    cswaite Solar Expert Posts: 46
    Re: Wiring Solar Panel?

    Thank You. Yes my charge controller does have reverse polarity feature.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Wiring Solar Panel?

    As Bill suggests,, buy and learn how to use a simple Digital volt/ohm meter. Checking the polarity of the panel then becomes a simple matter. Probes on one way should show positive voltage, probes reversed should show negative voltage.

    Not a bad idea to label the lugs then so that you aren't confused going forward. Red ID tape is a good thing to have around as well.

    Tony
  • cswaite
    cswaite Solar Expert Posts: 46
    Re: Wiring Solar Panel?

    What setting on the meter should I set it to? DC 10AMP? or?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Wiring Solar Panel?

    I don't have your meter--but as a guess you would set it to 10 Amp DC Current and move the "red" lead to the "10A" plug (used only for the 10 Amp full scale). The black lead should remain connected to the "COM" connection.

    Sample DMM tutorial.

    WARNING: Never connect an AMP/Current Meter (or DMM configured as an amp meter) across a large battery (like Lead Acid Storage Batteries)... At the very least you will fry your meter; at the worst you may cause a fire or explosion.

    Connecting solar panels to a DMM in current reading mode is a special case (solar panels are naturally current limited). As long as the maximum current of the solar panel is less than the maximum scale of the meter.

    Volt Meters, on the other hand, are very safe to connect across batteries.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • cswaite
    cswaite Solar Expert Posts: 46
    Re: Wiring Solar Panel?

    Thank you, explained well.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Wiring Solar Panel?

    for just checking for polarity you only need it to be in volts on any scale higher than the pv's rated oc voltage.
  • halfcrazy
    halfcrazy Solar Expert Posts: 720 ✭✭✭
    Re: Wiring Solar Panel?

    What brand panel is it?
  • cswaite
    cswaite Solar Expert Posts: 46
    Re: Wiring Solar Panel?

    It is a Sun panel. I figured out what the problem was.

    The wires must have snapped in the process of me pulling them hard through the flexible conduit tubing, I ran new wire in and tested everything and everything worked. I had everything correctly wired from panel to control

    Although, I made another post about it, that im only pulling 3.5AMPS at best with this 130 Panel!?!?