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Series-parallel balancing for parallel circuits scc

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  • Series-parallel balancing for parallel circuits scc

    I'm new here - am I correct that many are running grid tie systems? Mine is off-grid with solar charge controller and inverter. I've seen a lot of discussion of the panel input to the inverter. Is that a grid tie specific way of doing things?

    Okay, my real question...

    My SCC has two inputs for panels. I've come to understand that they are in parallel, so any arrays that I attached need to be well balanced.

    What is the best way of going about this? Setting up the arrays and checking the output voltage with a voltmeter?

    I'm also curious, I can't seem to find any diagram or video or information anywhere of using both the inputs. Even the manufacturers installation diagram shows multiple arrays going to combiner box and then only one circuit going to the solar charge controller.

    It seems peculiar to me.. and it's making me nervous. I want to make sure I'm doing things right. I had a near miss this week not understanding how this worked. I tried to connect imbalanced arrays and even at night, there was back feed to the low resistance circuit of about 10 amps (I think I understand this correctly! Any further explanation would also be welcome).

    Thanks in advance.

    If it's needed, I have a 48 volt 16s battery, 280 amp hours, 3,000 w inverter and 60 amp 150 volt charge controller.

    Oh, final question - is there any problem connecting a single panel to this system as long as there's not another array connected in parallel? I know it seems weird but I'm dealing with some battery balance issues and also haven't had to chance to fully test my equipment. I'm a student and I'm trying to get organized so I can finally get a full charge on the one day of the week I'm home all day to monitor the system and make sure charging turns off when it should.

    I'd like to be able to connect a single panel that I can be confident it's not going to overcharge while I'm gone all day but also maintain the level of charge.

    I know eventually I just need to get the full array set up so I can get charged in a single day. I'm new and honestly working with this much electricity is nerve wracking to me (but worth the effort!). I figure it's better to go in slow baby steps and avoid costly errors.

  • #2
    If your controller has two MPPT inputs then you should be able to connect two different strings of (not necessarily matched) panels. Be sure to keep the strings within mfg. specs. Multiple inputs are more than a combiner built into the SCC. What brand and model is your SCC?
    2 Kw PV Classic 200, Trace SW 4024 460ah,


    • #3
      Hmmm Thanks.

      SCC - PowMr 60amp mppt. I've been told by someone in another forum that the circuits are parallel. I guess that's why it's good I'm trying to get some confirmation.

      I did an experiment one night. I had two panels in series connected to one pair of terminals with a breaker switch. Then I connected a single panel to the other set of terminals also with a breaker switch.

      At night, there was close to 10 amps flowing to the panels when both breakers were on. I switched the one to two panel string off - and the power flow was reduced but still around 8 amps.

      I'm honestly not sure if my fridge was running or not which could account for the two amp difference.

      Definitely seemed like something unfriendly was going on! Not something I'm anxious to repeat

      Thanks in advance


      • #4
        • PowMr products are of questionable quality.
        • After looking into the SCC you described I saw this. "In order to reduce the cost of electricity caused by high current, PV and battery each have two terminals" I can only deduce from that statement that you DO NOT have two MPPT inputs. You have a pair of feeble connection points simply to save money over a single robust connection point capable of handling full maximum input and output current.
        2 Kw PV Classic 200, Trace SW 4024 460ah,


        • #5
          Yeah I might end up replacing it.

          Thanks for your help