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  • Parellel dramas

    Hi guys am chasing some advice for my off grid solar
    what I have to do is set up five solar panels in parellel but I have to place them side by side as ther is not enough space on my roof ...as the cables aren't long enough with mc4 connectors I was wondering if I could piggyback splice the cables and solder them together eliminating the mc4 connectors altogether except for the last panel your advice is greatly appreciated
    cheers

  • #2
    Anytime you place 3 or more panels/strings in parallel you need to fuse each panel/string of panels. You don't want to cut off the MC-4 connectors as that will void any warranty you might have..
    You need a fused combiner box at the array. They can be homebuilt for relatively little money.
    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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    • #3
      You can purchase extension cables with the correct polarity MC4 connectors already attached at each end. That will allow you to run all of the panels wiring to the combiner box.

      The last thing you want to do is solder any of the wiring. That won't last and will cause a failure.
      Last edited by SunEagle; 03-20-2017, 08:57 AM. Reason: addws last sentence

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      • #4
        As an alternative to a combiner box, if the combined current is less than 20 A, you can use branch connectors like this:

        https://www.amazon.com/Y-SOLAR-Conne.../dp/B01MXHHE4A

        Just make sure to put in an inline fuse for each panel before it is combined.

        https://www.amazon.com/E-accexpert-C...dp/B018I953ZG/
        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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        • #5
          Rule #1

          Never use a Prime Number of panel greater than 3 because it only leaves you one configuration of wiring all the panels in parallel. You need to loose or gain a panel. so you can configure them 2S2P or 3S2P. That way you do not need all that wire, fuses and combiners. Not to mention a lot more efficient and less expensive.
          MSEE, PE

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          • #6
            Ok thanks I'm new to this and it's very interesting things to do and don't ...I had no idea you couldn't run a prime number of panels something I think there should be more literature on and all the adapters that are shown on eBay go from 5 -1 which i find a bit strange now anyway thanks heaps for your advice

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            • #7
              Originally posted by Szabie View Post
              Ok thanks I'm new to this and it's very interesting things to do and don't ...I had no idea you couldn't run a prime number of panels something I think there should be more literature on and all the adapters that are shown on eBay go from 5 -1 which i find a bit strange now anyway thanks heaps for your advice
              You can run a Prime number if you do not know what you are doing. It will work, just not as good as it could. That is why manufactures make combiners to allow you to do that. They make a lot more money that way. It also means you have to buy a lot more wire and a lot larger wire. Cha-Ching. Just like Tobacco, Alcohol, and Ganja. Buy all you want, the more the better for the seller. Not their job to educate or look after you. All they want is as much of your money that you will part with. Less you know, the more money they make.
              MSEE, PE

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              • #8
                Can I combine two panels and run the other three seperatly to the combiner box it's just that I'm in western qld Australia nearest solar shop is about 500km away?I have one pair of mc4 connectors
                Last edited by Szabie; 03-20-2017, 10:25 PM.

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                • #9
                  Look up the "Skip Wiring" tequnique for solar panels, as a way to reduce the need for special cables.
                  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

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                  • #10
                    Leapfrog wiring of series wired panels.jpg

                    Works for serial wiring.
                    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                    • #11
                      Thanks but because it's totally off grid I have to go parellel because the voltage is to high it's feeding a Morningstar 60a Tristar to a magna-sine inverter from a 24v battery set up ...I've sort of got my head around it but it seems like everyday I'm taking 3 steps forward and two back ...learning heaps along the way and appreciate all the support tho !!!cheers

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