Mix match?

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  • Kenmx10
    Junior Member
    • Sep 2021
    • 1

    Mix match?

    I have a work trailer with 4 - 100 watt , 12 volt panels and a Renogy Wanders controller that is rated for 400 watts , so the controller is maxed out. I have a 300 watt panel that I would like to add if possible to give me 700 watts total. The 300 watt panel is 32 volts. If I got a different charge controller could I add the 300w panel or would there be issues combining the 32v panel with the 12v panels. Thx
  • SunEagle
    Super Moderator
    • Oct 2012
    • 15126

    #2
    Hello Kenmx10 and welcome to Solar Panel Talk

    Unless the CC is cheap it should take a higher input voltage from the panels and convert it to the battery rating without any issues.

    What I think may be a problem is if you have 2 different CC's connected to the same battery system. They may fight each other and you could lose some efficiency.

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    • 2BZ2Ranch
      Junior Member
      • Aug 2019
      • 3

      #3
      I’ve been lurking here for awhile and thought I might make a suggestion.
      Yes, you would have an issue - but only as far as efficiencies go.
      As you know for panels in parallel the amps are additive. However, the total watts are calculated by the LESSER voltage. So (using simple Ohms/Watts law) 400 watts divided by 12 volts = 33.3 amps; 300W dividend by 32V = 9.4A; therefore, 33.3A + 9.4A = 42.7A,,,, times 12V = 512W,,,, divided by 700W (original panels’ wattage) = 0.73 x 100 = 73% efficiency. Your new controller can handle it but you might be better off selling one of your arrays and buying a matching panel(s).
      Just thinking out loud.
      Dave
      Last edited by 2BZ2Ranch; 09-27-2021, 12:17 AM.

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      • 2BZ2Ranch
        Junior Member
        • Aug 2019
        • 3

        #4
        I should have added what would happen if you put your 12V 400W array (@33.3A) in series with the 32V 300W panel (@9.4A). Panels in series the voltage is additive but the wattage is calculated with the LESSER amperage. So 12V + 32V = 44V x 9.4A ~= 414W. That would be worse with an efficiency less than 60%.
        Dave

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        • checkthisout
          Member
          • Mar 2019
          • 76

          #5
          Originally posted by Kenmx10
          I have a work trailer with 4 - 100 watt , 12 volt panels and a Renogy Wanders controller that is rated for 400 watts , so the controller is maxed out. I have a 300 watt panel that I would like to add if possible to give me 700 watts total. The 300 watt panel is 32 volts. If I got a different charge controller could I add the 300w panel or would there be issues combining the 32v panel with the 12v panels. Thx
          Absolutely no issues at all.

          The only thing I would suggest is purchasing a larger then needed second charger controller in case you decide you want to add more or larger panels in the future.

          In Edit: I want to clarify since you weren't clear that you would need to run 2 different charge controllers, one for your 12V panels and a new one for your 32V panel.

          There is no issue having two different charge controllers feed into the same battery.

          You cannot combine the 12V and 32V panel into the same charge controller.
          Last edited by checkthisout; 10-04-2021, 03:06 PM.

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