grounding pv

kenkathy
kenkathy Registered Users Posts: 9 ✭
in Solar Beginners Corner #1
I'm planning to install a new pv array. I have a combiner box in the outbuilding mounted by the inverter. I was planning to run the mc4 cables through an existing penetration in the roof and in metal conduit to the combiner box. My question is should I run the 6 awg pv grounding wire in the conduit to the combiner box grounding bar or should I run this separately to the common system ground either inside or outside the building?
thanks
Ken
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  • GreenPowerManiac
    GreenPowerManiac Solar Expert Posts: 453 ✭✭✭
    #2
    Re: grounding pv

    If it's an Earth ground from your PV system for lightning strikes it'll go straight into the combiner box grounding rod. Don't hook something like this to a neutral bar, or common ground, it can get dangerous. A neutral bar or common runs A/C and should be a separate system from D/C altogether.
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  • kenkathy
    kenkathy Registered Users Posts: 9 ✭
    #3
    Re: grounding pv

    I should be more specific. The pv array is 40 feet from the main structure on top of a dedicated outbuilding. I need to have an equipment ground for the pv array. I'm using the weeb system for the array. I was planning to run bare copper grounding wire through the roof penetration with the mc4 cables in metal conduit to the combiner box in the outbuilding. I would connect that to the earth ground. I have seen multiple references to running a separate earth ground directly to a grounding spike outside of the building for additional lightening protection. Is this standard or recommended?
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  • GreenPowerManiac
    GreenPowerManiac Solar Expert Posts: 453 ✭✭✭
    #4
    Re: grounding pv

    "I have seen multiple references to running a separate earth ground directly to a grounding spike outside of the building for additional lightening protection."


    I'd go with that option so long as it's not connected to any power source. This way you're giving the lightning an out route.
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #5
    Re: grounding pv
    kenkathy wrote: »
    I should be more specific. The pv array is 40 feet from the main structure on top of a dedicated outbuilding. I need to have an equipment ground for the pv array. I'm using the weeb system for the array. I was planning to run bare copper grounding wire through the roof penetration with the mc4 cables in metal conduit to the combiner box in the outbuilding. I would connect that to the earth ground. I have seen multiple references to running a separate earth ground directly to a grounding spike outside of the building for additional lightening protection. Is this standard or recommended?

    For a 40' separation, I would go ahead and drive a ground rod at the outbuilding. you can run the ground down from the PV framework as you described to the combiner box chassis (and probably then to the inverter chassis as well) and then to the ground rod.

    If you are backfeeding a house main panel, then do not have neutral to ground bonded in the inverter - that should happen only in the main house panel.

    The inverter will almost certainly need an equipment grounding conductor between its chassis and the main house panel as well.
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