Can you junction box the return PV wire? or are MC4 connectors required?

Can one simply buy a plastic junction box, bolt it onto the underside of a ground mount frame and run the last solar pv panel return wire into it and then wire nut a longer length PV 10 gauge wire for return to the breaker box?

Seems to be code compliant to me, but maybe solar has some wierd rule?

Comments

  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: Can you junction box the return PV wire? or are MC4 connectors required?

    I'm sure if you check your module installation instructions, they will say that if you cut off the supplied connectors, it will void the warranty.
    Just buy a short "extension" wire from your friendly solar distributor that has the right connectors on each end and cut it in half to get your needed home run wiring.
  • BB.BB. Super Moderators, Administrators Posts: 30,642 admin
    Re: Can you junction box the return PV wire? or are MC4 connectors required?

    But yes, you can use a "Rated" junction box and make your local array to main run connections there.

    And the suggestion is to purchase Male/Female cables that are long enough to cut in 1/2 and run from the panels to the J-Box.

    MC Interconnect Cables for Solar Electric Panels

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: Can you junction box the return PV wire? or are MC4 connectors required?

    is there some kind of special rated box? Or just a standard one from home depot is fine?
  • BB.BB. Super Moderators, Administrators Posts: 30,642 admin
    Re: Can you junction box the return PV wire? or are MC4 connectors required?

    probably rated for outdoor... Do you need plastic (no rust and not great in heat) vs metal (good electrical grounding and good heat resistance, possible rust/corrosion from steel/aluminum box)?

    My vendor years ago used a plastic j-box on my roof, in full sun, to join array cables to metal conduit. Still working 8+ years later.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Can you junction box the return PV wire? or are MC4 connectors required?
    BB. wrote: »

    My vendor years ago used a plastic j-box on my roof, in full sun, to join array cables to metal conduit. Still working 8+ years later.

    -Bill
    In standard AC wall boxes, I think that the gray ones have good UV resistance, not so sure about the blue ones.
    SMA SB 3000, old BP panels.
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