No announcement yet.

Motor Home Solar Panel

  • Filter
  • Time
  • Show
Clear All
new posts

  • Motor Home Solar Panel

    Hi, i need some advice, i bought a 27 year old motorhome which has a 36 cell solar panel on the roof, it's sealed down so can't see any information.

    When i bought the MoHo recently there was no charge controller for the solar panel, it was just connected directly to 2 batteries, which one is dead ...... so i bought a 30A PWM solar charge controller and a new 12v/125Ah leisure battery, i put a tester on the solar panel to check polarity and voltage, the voltage shows about 19v coming through, but wont show the Amps.
    I connected everything up and the Icon shows for the solar panel but it's not charging the battery ..
    i also recently purchased an MPPT Blue Solar controller 75/15, so decided to install this just in case the PWM controller was faulty, when i connect the battery the green LED shows, but when i connect the PV panel the yellow light does not light up, i've also checked to see if the wires were connected correctly.
    Is the solar panel damaged due to having no controller before?
    any help would be appreciated.
    Last edited by Zodiac; 10-05-2017, 05:29 PM.

  • #2
    Do you know how to measure ...
    a) Voltage - Open Circuit
    b) Amps - Short Circuit
    for a Solar Panel ( under full sun ) ?

    Voc = ~22 Volts
    Isc = ~4 Amps or more ?

    This will tell if the Solar Panel is OK or Defective.
    Last edited by NEOH; 10-05-2017, 07:41 PM.


    • #3
      Sure sounds like a bad panel, but for completeness, what was the 'tester' used to try to measure amps? Does that tester measure amps correctly with anything else (not going to tell you how many times I've seen DMMs with blown fuses inside that the owner was unaware of). Apparently measuring amps is not something that a lot of meter owners do a lot.


      • #4
        Thank you for the replies Neoh & AzRoute66, Yes Neoh we have full sun in Spain, no clouds in the sky, when i put the meter selection to DCV i get 19.7v, when i put the meter selection to DCA i get a blank screen or the number 1, that's on any selection in the DCA area, when i connect the PV panel to MPPT charge regulator, which only has a green light for the battery and a yellow light for the PV panel ...... the yellow light does not light up at all, even if the battery is at 10.1v ... i'm a novice at this, so only doing what i can to my knowledge.


        • #5
          Most meters require you to Move the red lead from the Voltage, ohm, Hz port to the 10 amp port to measure amps.

          Volt meter.jpg
          2.2kw Suntech mono, Classic 200, NEW Trace SW4024


          • #6
            thank you Littleharbor, i will try this


            • #7
              Also if your meter has AC or DC amp choices on the dial you must chose DC amps. The one pictured does AC and DC together, as shown by the straight and curving line. AC is the curving line. DC would be a straight line over a dotted line, Choose 10 amp setting in this case. DVM volt meter.jpg

              Last edited by littleharbor; 10-06-2017, 07:33 AM.
              2.2kw Suntech mono, Classic 200, NEW Trace SW4024


              • #8
                I almost never try to use the amp meter scale, too many problems getting it connected to
                the circuit and too much risk of serious problems in the process. Instead I bolt a calibrated
                shunt (or maybe just a carefully chosen resistor) into the circuit, then use my millivolt meter
                to measure the shunt output voltage; translate that to amps.

                For general checking of the array, I use a DC clamp on meter. Bruce Roe


                • #9
                  DC clamp on meters are not expensive and will provide a much safer way to measure the current going through a wire. I purchased a UNI-T UT203 for about $30 when I got into RC model flying a few years ago. It is rated up to 400amps and works just fine on my solar / battery systems.