How to ground SunnyBoy 6000US inverters?

aluminumwelder
aluminumwelder Registered Users Posts: 10 ✭✭
in General Solar Power Topics #1

I've been trying to understand the instructions for wiring up a pair of older sunnyboy 2008 6000us inverters to a 10KW GT Residential picnic shelter about 35 feet away from the main 200a home panel. I thought I was supposed to have an 8' long grounding rod at the solar panels which was attached to the solar panel frames. But these instructions seem to suggest I need to run the 6awg grounding cable 35 feet back to each inverter???   My main concern is that the inverter's  GFPD will work. Can anyone help me with correct wiring. 
I currently do not have any wires attached to either A or B of these terminals. I have them grounded at the picnic shelter like photo shows. 


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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Going to have to ask your inspector what he wants.  I don't like to run an equipment/frames/mounting/Lightning Rod ground thru a box with household wiring.  I'd rather take that lightning right to earth, not thru a box.
    Powerfab top of pole PV mount | 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 ||
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,917 ✭✭✭✭✭✭
    #3
    Where do you get #6 from?
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • aluminumwelder
    aluminumwelder Registered Users Posts: 10 ✭✭
    #4
    any hardware store sells 6awg
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,917 ✭✭✭✭✭✭
    #5
    In your design, where do you get #6?
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • aluminumwelder
    aluminumwelder Registered Users Posts: 10 ✭✭
    #6
    not sure I understand your question? I got it from home depot. why doe sit matter?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #7
    I think Dave is asking what manual/NEC code is suggesting 6 AWG cable for grounding (not that I disagree with your choice--From the little I know)...

    I suggest 6 AWG as a minimum for grounding to a ground rod/system lightning grounding.

    "Real/Professional" lighting grounding systems (lightning rods, ground rods/plates, etc.) can use much heavier/braided cables.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • aluminumwelder
    aluminumwelder Registered Users Posts: 10 ✭✭
    #8
    #6 is the minimum size, you can go higher like #4. The reason is due to physical strength, smaller gauges are too flimsy. NOt sure where it is in NEC, but somewhere in 250 I guess. several sources state this> i think I read it here Photovoltaic System Grounding - Florida Solar Energy Center (solarabcs.org)
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #9
    Yep... agree with your reasoning from that I have seen... Years ago (may still be true), for residential size main panels, 8 AWG was also allowed--As long as the 8 AWG was insulated cable (bare #8 was not allowed). But I still suggest #6 is a better solution for your reasons (and an article I found years ago did some research of lightning strikes in Germany (as I recall)--And there were examples of 8 AWG cables getting vaporized and few (or no) instances of #6 or heavier cables surviving).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,917 ✭✭✭✭✭✭
    #10
     Ground rod is Number 6 solid no conduit, or stranded with conduit for protection. That is not what I think you were asking. I think you are talking about the connection between the two ground bars or ground systems. For offgrid we want them connected but not any thicker wire than is required. Typically this is the size of the wiring out of the combiner, array wire size, or what the inspector wants, if it is inspected at all.

    The point is if lightning does hit, we do not want to get it into the home any easier than possible. We do want the advantage of everything being at the same potential to not attract the strike. There are many opinions on all of this. Mine is born out of good experience for 100's of offgrid homes.   For grid apps it is what the inspector wants.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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