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  • DIY junction box

    Hi all,

    after looking for a larger junction box online, i wasn't able to find any that suits my need for a number of ports for wires.
    Since i decided that i will not have a junction box on every panel, i decides to put all wires from 8 panels into 1 box.

    Here is rough schema.
    junctionbox-001.jpg

    Please share your thoughts on this.
    Any comment is appreciated.

  • #2
    I can't figure your schematic out. If you have more than 3 parallel circuits, you need breakers or fuses. Diodes - for what ?
    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
      Thanks for pointing this. I see the error now.

      I had initial idea of of joining 2 panels in series, and make 4 pairs in such way (which would give me 40V 8A per pair).
      Then those 4 arrays/pairs connect in parallel which would give me 40V 32A in total. - that's why i have left 4 bypass diodes by mistake.

      Later i changed my mind and thought it would be easier to join 4 panels in parallel and then join those 2 array in series - but diodes i forgot from previous plan.

      Here is the new schematic but i'm not sure i got it correct either. Please take a look:
      jbox 001.jpg

      Why do i need breakers or fuses ?
      Thank You on reply.

      Comment


      • #4
        Please, can you at least post a link to some tutorial or article about fuses in solar panels ?

        Comment


        • #5
          Originally posted by borosane View Post
          ....

          Why do i need breakers or fuses ?
          Thank You on reply.
          one panel ---> charge controller & Loads---> FUSE ---> Battery +

          adding a 2nd panel in parallel to the first no PV array fuses needed

          BUT when you add a 3rd parallel panel, then if 1 panel gets a fault, the power of 2 other panels feeding into the fault can start a fire. So more than 2 parallel panels, needs protection. At least a fuse, but a DC breaker is nice because it can occasionally be used as a switch for testing purposes.
          The fuses or breakers get installed near the panels in a Combiner Box which is a common solar supply item.SolarPanelFire_1c.jpg
          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

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