Need second opinion

stumpy40
stumpy40 Solar Expert Posts: 35 ✭
in Solar Beginners Corner #1
I have a 180' run from array to house and while I know its generally better to make my DC run the longest. I would like to make sure I'm doing my math correct.

When I do the math it seems I can get by with 6awg wire and not 4awg as I originally thought. Could someone help with a second look?


Question regarding combiners....Does midnite solar MVNP6(sp) come with a way to have 2 outputs? I have a total of 6 strings and would like to only use one combiner.

I was thinking of mounting combiner using 4"ubolts and unistrut...anyone see a problem with this?

This will be a GT system...69 Trina 230's and 2 SMA7000's...no batteries. Pole mounted
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,623 admin
    #2
    Re: Need second opinion

    What is your array setup (X by Y series parallel across two inverters)? Do you have the Trina Imp/Vmp handy?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • stumpy40
    stumpy40 Solar Expert Posts: 35 ✭
    #3
    Re: Need second opinion

    3 strings of 12, and 3 strings of 11
    Trina info is Vmp 29.8v and Imp is 7.72A
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  • dsp3930
    dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    #4
    Re: Need second opinion

    From NAWS description for the MNPV6:

    (It) Will accept six 150VDC MNEPV breakers or four 600VDC touch safe fuse holders. Includes 14 position PV negative bus bar, 14 position ground bus bar, 120 amp Plus bus bar for breakers and 60 amp bus bar for fuses. 4 pounds, 9" x 14" x 4".

    My comments:
    If your string voltage is over 150v (which it appears to be) then you would have to use the 600VDC touch safe fuses. Only 4 of these can fit in each combiner.
    This means you would need a second MNPV6 combiner.

    I'd check with MidniteSolar.com on their forum to see what they would recomend.

    David
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