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38V or 36V Solar panel? And how to charge it on 6V Batteries....

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  • 38V or 36V Solar panel? And how to charge it on 6V Batteries....

    Okay, I know It sounds stupid... But a friend offgrid had someone order a solar kit for him. I know a little about DIY 12V and 24V Solar stuff.... But I am not familiar of bigger setups.
    I know what I am about to explain is REALLY off and wrong. So please help me help him get the right stuff to finish his setup. He's spent a lot already, and the guy that bought the stuff is a self taught solar guy off of criagslist... (I KNOW!!!! RIGHT!!!!)

    my friend currently have these stuff:
    SOLAR PANEL:
    - GCL SOLAR Brand
    - 335WATT
    - 38V
    - 8.82A
    - Model is GCL-p6/72335
    - TOTAL OF 12 PANELS in Parallel

    Combine Box:
    - Liket Brand, Prewired
    - with 6 Breaker rated 20A each
    - Each breaker handles 2 panel

    Now HE HAVE A 80A Charge Controller (We don't know how the Volt, because it doesn't say it anywhere. Weird....)

    Then to 8 Batteries... AND, here's the Specs;
    - Trojan Brand, Model SSIG 06 475
    - 6VOLT
    - 475 AH
    - They have tried to Series it and Parallel....

    The Power Inverter, is a 5000W, 24V unit.
    What I don't understand is, he said they managed to get power from the batteries and had the power inverter worked for a day and overnight, then after that it just never worked anymore.
    That's when they thought something is wrong with the batteries and started playing series and paralleling the batteries... So I was not sure if they used parallel or series at first for the batteries.
    Besides, can a 24V power inverter really work with 6V batteries? How?

    tell us what he needs to change, do what to get the panels to charge his battery bank.. (I personally think the batteries isn't suitable for the setup, but...) is his 38V panels is considered a 36V so that he should stick with 36V parts?

    Please no harsh comments... try to help him out... Thanks. He's offgrid.
    Last edited by thaomart; 04-20-2019, 04:22 AM.

  • #2
    Hello thaomart and welcome to Solar Panel Talk

    I see a couple of issues with that equipment. The 36V - 38V panels are ok but you have too many for a single 80amp CC to charge a 24V battery system.

    Most of the quality CC's will be able to charge batteries at 12V, 24V & 48V automatically. But with a 24V inverter you are locked into a 24V battery system.

    An 80A MPPT will probably have a maximum wattage input of about 2000 watts (80A x 24V = 1920watts), so you will only be able to use 6 of those 335W panels wired 3S2P or 2 parallel strings of 3 in series provided your MPPT can accept 150V DC input. Otherwise they would need to be 2S3P or 3 parallel strings of 2 in series.

    8 of those 475Ah batteries wired as 4S2P (4 in series in 2 parallel strings) will be a little big for 80 amps of charging but workable.

    Maybe other off grid people can chime in concerning the best wiring and use of that equipment.

    Comment


    • #3
      You're going to need to tell us what charge controller this is. Brand and model? Photo? This has everything to do with how to wire up your panels.
      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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      • #4
        Sounds like your experience with 12 and 24 volt stuff, as you call it is almost non existent. If you think 6 volt batteries won't run a 24 volt system then tell me, where do you get 24 volt batteries?
        2.2kw Suntech mono, Classic 200, NEW Trace SW4024

        Comment


        • #5
          Originally posted by littleharbor View Post
          Sounds like your experience with 12 and 24 volt stuff, as you call it is almost non existent. If you think 6 volt batteries won't run a 24 volt system then tell me, where do you get 24 volt batteries?
          I think the OP's question concerns the higher voltage panels being able to charge a lower voltage battery system. I would hope they understand that they need to wire 4 of those 6V batteries in series to get a 24V battery but in reality they should go with a 48V battery system and then can use all of the panels with a quality 80A MPPT CC.

          But you are correct. Getting the equipment make and model info will help direct them to the best system.

          Comment


          • #6
            Another option would be to run the 8 batteries in series for a 48v bank and see if you can exchange the 24v inverter for a 48v unit.

            Comment


            • #7
              This is the line that I'm referring to,
              "Besides, can a 24V power inverter really work with 6V batteries? How?"
              2.2kw Suntech mono, Classic 200, NEW Trace SW4024

              Comment


              • #8
                Originally posted by littleharbor View Post
                This is the line that I'm referring to,
                "Besides, can a 24V power inverter really work with 6V batteries? How?"
                Yes. I see where that statement can be of a concern.

                Hopefully the OP will come back and continue the converstaion.

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