Stringing MC-4 wire between solar panels, strings, to the junction panel.

Organic Farmer
Organic Farmer Solar Expert Posts: 128 ✭✭
in General Solar Power Topics #1
When stringing MC-4 cable panel-to-panel making series strings, and when running cable from strings to the junction panel [or combiner box], is it customary to run it all inside grounded conduit?

The same question applies to running MC-4 cable from the junction box to the power center panel?

Thank you.
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  • Alaska Man
    Alaska Man Solar Expert Posts: 252 ✭✭
    #2
    Re: Stringing MC-4 wire between solar panels, strings, to the junction panel.

    I was told it wasn't needed. The MC4 is rated for exposure to the elements. Mine are not in contact with the ground and are not run where they could get in the way of foot or vehicular traffic. They can be direct buried or so I was told. The good thing about running them in a conduit is it's a lot easier to change them out if you ever had the need.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #3
    Re: Stringing MC-4 wire between solar panels, strings, to the junction panel.
    Organic Farmer wrote: »
    When stringing MC-4 cable panel-to-panel making series strings, and when running cable from strings to the junction panel [or combiner box], is it customary to run it all inside grounded conduit?

    The same question applies to running MC-4 cable from the junction box to the power center panel?

    Thank you.

    MC-4 is a connector rating, not a cable rating. If it is USE-2 or PV wire you are talking about, it is rated to be exposed to sunlight, so it it is not necessary to put it in conduit going into the J box or combiner. From the J box to the power center, most folks use something like THWN-2 wire, which does need to be in conduit. All metal conduit needs to be grounded.

    FWIW, USE-2 does come in colors, but solar guru John Wiles recommends that only black be used if it is exposed to sunlight.
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  • Organic Farmer
    Organic Farmer Solar Expert Posts: 128 ✭✭
    #4
    Re: Stringing MC-4 wire between solar panels, strings, to the junction panel.

    These MC4 Extension Cables are made with black #10 AWG USE-2 sunlight resistant cable.

    I will likely use 2AWG wire in conduit between junction box and power center.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #5
    Re: Stringing MC-4 wire between solar panels, strings, to the junction panel.
    Organic Farmer wrote: »
    These MC4 Extension Cables are made with black #10 AWG USE-2 sunlight resistant cable.

    I will likely use 2AWG wire in conduit between junction box and power center.
    The extension cables are fine out of conduit, but #2 (THWN-2 or similar) must be in conduit.
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