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Small system for cabin, first atempt. Advise welcome!

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  • Small system for cabin, first atempt. Advise welcome!

    This is my first solar project. I've tried to do my homework the past few weeks and this what I have so far, but I still have a few questions. Let me know if you see any pitfalls here.


    This is for a small one room cabin. The intention is to charge phones/laptops, run a 24V DC fan in summer, and interior and exterior lights. (DC, Probably LEDs)
    I have two 230W hyundai solar panels that I intend to wire in parallel to a Xantrex C-60 PWM controller to charge two 12V 200ah AGM batteries wired in series. I'm planning on using 6 AWG wire, I'm guessing about 20 foot from the panels to the controller then another 4 foot to the batteries. The C-60 has an optional battery temp sensor.


    Is this something you would feel comfortable leaving unattended for several weeks? Should there be some sort of cooling fan on the controller or batteries for 90° summer days?

    Surely there needs to be a fuse or two in here some where, would 60 AMP be appropriate between the PV and controller and between controller and battery?


    Thanks!
    JB

  • #2
    Yes, you should have a 20 - 25A between the Battery and the Charge controller . Just one fuse on the + wire is enough. 2 panels in parallel do not need a fuse.
    for longest battery life, you should use a BTS made for the C-60, and disable the automatic EQ cycle . You should monitor the specific gravity to decide when to EQ the batteries.

    While away, all loads should be disconnected , but the charger should remain connected, to prevent self-discharge of the batteries, and the shortened life caused by low voltage levels.
    You have a quality charger C-60, and it should be fine to leave it tending the batteries.
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment


    • #3
      Originally posted by Mike90250 View Post
      Yes, you should have a 20 - 25A between the Battery and the Charge controller . Just one fuse on the + wire is enough. 2 panels in parallel do not need a fuse.
      for longest battery life, you should use a BTS made for the C-60, and disable the automatic EQ cycle . You should monitor the specific gravity to decide when to EQ the batteries.

      While away, all loads should be disconnected , but the charger should remain connected, to prevent self-discharge of the batteries, and the shortened life caused by low voltage levels.
      You have a quality charger C-60, and it should be fine to leave it tending the batteries.
      What did you use to decide fuse A?

      Comment


      • #4
        Originally posted by 124C41 View Post


        Is this something you would feel comfortable leaving unattended for several weeks? Should there be some sort of cooling fan on the controller or batteries for 90° summer days?


        JB
        Your batteries will be floating most of the time, so not much heat will be generated. You will probably just want to open the compartment when you leave. Have you calculated the charge rate from your panels?

        Comment


        • #5
          Originally posted by donald View Post
          Your batteries will be floating most of the time, so not much heat will be generated. You will probably just want to open the compartment when you leave. Have you calculated the charge rate from your panels?

          I have not!

          Comment


          • #6
            So if I'm doing the math right. The two panels Imp : 15.8 , so charge rate would be C/12.6 ?

            Comment


            • #7
              Originally posted by 124C41 View Post
              So if I'm doing the math right. The two panels Imp : 15.8 , so charge rate would be C/12.6 ?
              The math is:

              Charge rate from your panels = Battery Bank Amps / Charging amps to Battery
              Charging amps to Battery = Total PV Watts / System Voltage

              Your System:

              460W/24V= 19.16
              200AMP / 19.16 = C/10.43

              Comment


              • #8
                Originally posted by mschulz View Post
                The math is:

                Charge rate from your panels = Battery Bank Amps / Charging amps to Battery
                Charging amps to Battery = Total PV Watts / System Voltage

                Your System:

                460W/24V= 19.16
                200AMP / 19.16 = C/10.43
                He's using a PWM charge controller so he has the calculation right using the IMP of the panels. Your way is using an MPPT controller.

                WWW

                Comment


                • #9
                  Originally posted by Wy_White_Wolf View Post
                  He's using a PWM charge controller so he has the calculation right using the IMP of the panels. Your way is using an MPPT controller.

                  WWW
                  Ah, I didn't see that. My Bad.

                  Comment


                  • #10
                    Originally posted by Wy_White_Wolf View Post
                    He's using a PWM charge controller so he has the calculation right using the IMP of the panels. Your way is using an MPPT controller.

                    WWW
                    Dang, I liked his math better. I'm guessing a MPPT would be that much more efficient?

                    I picked up the PWM controller a couple of hours ago and 80FT of 6 AWG wire. (Wire is expensive...)
                    The 20 Amp fuses / holders I have been looking at all seem puny and would be hard to attach to the 6 AWG. Does anyone have a suggestion on the style of fuse and size of wire between the controller and batteries? Or maybe a breaker.

                    Thanks for your responses BTW.

                    Comment

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