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  • Motor home Solar power

    Hi everyone i am new to this forum, so apologies for asking questions that has probably been answered many times. We like to get away in our motor home as often as we can and like many, we are now going off grid a lot more. I purchased a solar kit to keep the leisure battery topped up which included a 100w solar panel and a LS1024B EP solar charge controller, i also added a MT50 monitor. I was surprisingly pleased with the equipment on a sunny day it is generating 18.2v / 2.8A which is keeping up with our usage, unfortunately on a dull day when the charge drops its not keeping up.
    Our off grid our leisure battery powers - the TV, Satellite box,lights, and except for short blasts of the water pump the rest is powered by gas.
    So my questions
    > could i add another 1 or 2 100w panels to compensate for the dull days:
    > would my current 10A charge controller be sufficient
    > would changing my charge controller to MPPT benefit
    Can any one give advice ??


  • #2
    A 10 amp PWM controller won't handle another 100 watt panel. A 20 to 30 amp MPPT controller will take two to four 100 watt series wired panels and give you considerably more charging power. You need to ensure your panels are placed where they wont be shaded. Stay away from A/C units and roof vents. While cumbersome, if you deploy your panels on the ground with tilt out legs you may be able to park in the shade and stay cooler.
    One suggestion on your satellite receiver draws power all the time whether on or off. Unplug it when not actually watching.
    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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    • #3
      Before you add any solar, install and electronic Battery isolator so the engine alternator can charge the battery. 1 hour engine run time will generate more power than your panel generate in a week. Your PWM controller turns your 100 watt power into a 60 watt panel, and at 10 amps is maxed out with a 100 watt panel.

      Additionally if your controller outputs 18.2 volts, means your battery is TOAST. At 2.5 amps into a 12 volt battery is a whopping 30 watts.
      MSEE, PE

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      • #4
        Hi all thanks for the reply, got my answer regarding the charge controller, i have purchased another 100w 12v panel you previously stated that my charge controller would not support 2x100w panels, i am thinking of purchasing the EP Solar BN range mppt charge controller 20A so my question
        Would this charge controller be sufficient for my 2X100w Panels
        would i be better to wire them in series or parallel

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        • #5
          Yes it will. If you're reasonably sure shading wont be an issue in their placement then absolutely series wire them. 200 watts isn't a large amount of power (actually, lying flat on an RV roof you may never see 200 watts coming in to the CC), so don't expect to be the dry camping power company. You may consider the 30 0r 40 amp version. Your batteries will stay charged between camping trips as long as you have the RV in the sun. The panels will help get your batteries recharged daily but keep in mind if you use more power than you're making you are deficit charging and may need the generator to supplement the solar.
          If you don't have the isolator Sunking suggested you should look into one.
          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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          • #6
            h just a quick question would the ( EP Solar BN range mppt charge controller 20A) be compatible with a Sharp- ND-R250A5 - 250w panel VOC- 37.6V ISC- 8.68A

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            • #7
              Being an MPPT controller, yes. It has a max Voc. of 150 volts.
              This combination would work for a 12 volt charging system. Problem is You can't add any more solar power because of it being a 20 amp controller. 250 watts divided by 12 volts is 20.83 amps. If you're sure that's all you need then, fine. If you find out you're underpowered for your needs you'll need to start over with a new, larger controller.
              2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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              • #8
                Hi thanks the system you suggested is working great on the motor-home, the charge is keeping up with the usage, i know you said no more panels can be added on a 12v system with the 20A controller, out of curiosity if i added a battery and changed to 24v system could i add another panel in series with this controller ??
                The reason i am asking is because the 250v Panel i won at a local auction when i went to pay the told me that there was five panels in total, they only brought one in on the day so i think i got a bargain, i will probably ask for your expertise what i can do with these, once the motor-home project is complete.

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                • #9
                  If switching to 24 volts you can add another panel, and in series. Thing is with a 24 volt system you are going to have problems with the 12 volt loads you have onboard. Some of the newer LED lighting can work on 24 volts but what about the water pump, stereo and fans?
                  2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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