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  • Solar Set Up Help

    Hi everyone! I am trying to figure out what all I need for my solar set up and I could really use some help!

    I am using a 24V 300W solar panel, with a 100|20 MPPT charge controller hooked up to two 12V AGM batteries connected in series. Then I will power various 12V appliances and a 24V inverter.

    Main questions:
    a) Is that charge controller the right size?
    b) Do I need a step down converter in there somewhere?
    Any other general thoughts/ comments about this set up would be greatly appreciated!

  • #2
    Are you using a single 24v 300 watt PV panel ?
    What size AGM Batteries ?
    You size your inverter per your loads.
    How are you going to power 12 volt loads with a 24 volt battery bank?

    Comment


    • #3
      Originally posted by NEOH View Post
      Are you using a single 24v 300 watt PV panel ?
      What size AGM Batteries ?
      You size your inverter per your loads.
      How are you going to power 12 volt loads with a 24 volt battery bank?
      Yes a single panel
      They are 200Ah batteries
      A 300W inverter, only use to charge laptop/phone and maybe for a small kitchen appliance
      And thats why I am wondering if I need a step down converter 24V to 12V

      Comment


      • #4
        Having 12V loads powered by a 24V battery system will cause an unbalance and premature battery failure.

        Comment


        • #5
          You need higher voltage than a single 24 volt panel produces to charge a 24 volt battery through an MPPT controller, at least for optimum charging.

          Question, is the 300 watt panel a 60 cell or a 72 cell panel?
          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

          Comment


          • #6
            Originally posted by SunEagle View Post
            Having 12V loads powered by a 24V battery system will cause an unbalance and premature battery failure.
            Right, so could I use a step down converter from the battery to the 12V loads?

            Comment


            • #7
              Originally posted by SunEagle View Post
              Having 12V loads powered by a 24V battery system will cause an unbalance and premature battery failure.
              A 24 Volt to 12 Volt DC converter will easily solve this problem ...

              Comment


              • #8
                Originally posted by littleharbor View Post
                You need higher voltage than a single 24 volt panel produces to charge a 24 volt battery through an MPPT controller, at least for optimum charging.

                Question, is the 300 watt panel a 60 cell or a 72 cell panel?
                I think 60, they're PERC solar cells, which I read were more efficient.

                Comment


                • #9
                  Originally posted by NEOH View Post

                  A 24 Volt to 12 Volt DC converter will easily solve this problem ...
                  Thank you NEOH!
                  Now my next question is where do I put the converter in all of this? After charge controller? From batteries to fuse box?

                  Comment


                  • #10
                    Originally posted by tigerremod View Post

                    I think 60, they're PERC solar cells, which I read were more efficient.
                    Then you have a couple issues. One, a single 24 volt panel isn't high enough voltage for an MPPT controller, and two, a 60 cell panel is considered more of a 20 volt nominal panel.

                    Easy solution. get one more panel. and series wire them.
                    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                    Comment


                    • #11
                      PV Panels => Fuse => Charge Controller => Fuse => 24 v Battery

                      24 v Battery Bank => Fuse => 24 v Inverter => Fuse => 120 V AC appliances
                      24 v Battery Bank => Fuse => 24-to-12 V DC down converter ( properly sized by amps ) => Fuse => 12 V DC devices

                      "Fuse" may be a Fuse or a Circuit Breaker
                      Use "DC Rated" fuses for DC circuits
                      Use "AC Rated" fuses for AC circuits

                      Comment


                      • #12
                        Please reply with ...
                        a) The exact model # of the PV Panels
                        b) The exact model # of the MPPT Charge Controller
                        Last edited by NEOH; 08-26-2019, 10:20 AM.

                        Comment


                        • #13
                          Originally posted by NEOH View Post

                          A 24 Volt to 12 Volt DC converter will easily solve this problem ...
                          Yes. The OP could use that type of converter to generate 12V. But how big should it be? That will depend on the 12V loads.

                          Bigger problem is what littleharbor has pointed out. A single 24V panel will not be enough to charge a 24V battery system.

                          Comment


                          • #14
                            Originally posted by NEOH View Post
                            Please reply with ...
                            a) The exact model # of the PV Panels
                            b) The exact model # of the MPPT Charge Controller
                            Not sure of exact model numbers but I can tell you what they are...
                            a) Renogy 300W 24V Monocrystalline Panel
                            b) Victron SmartSolar MPPT 100|20 Solar Charge Controller

                            hope that helps

                            Comment


                            • #15
                              I don't have room for another panel as this is going on top of my camper and the 300w is large, I know of people that have the same set up but their batteries are wired parallel, not sure if that makes a difference. I've heard that batteries should be wired in series.

                              Comment

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