Grounding of PV panels

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NBDrancher
NBDrancher Registered Users Posts: 19 ✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
I am installing a 2nd array of 3 x 285 watt panels on a pole mount with a Midnite Solar combiner box/lightning arrestor. I mounted the box to the pole of my first array ( 4 x 175 watt panels). The installer did not ground them when he did the job and I want to ground it all but am not sure if I should drive a ground rod right near the pole or run a separate wire to the ground rod at the small building that houses the Outback inverter, charge controller, batteries and disconnects. Any help would be appreciated.

Outback VFX3524 inverter, Xantrex C-40 charge controller, Iota 24 volt charger, Siemens panels, German Solar panels, Pre-Formed Products pole mounts, Deka 6 volt batteries, 21kw Perkins/Borg Warner diesel generator.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    How deep is the pole in the ground ?  packed dirt or concrete ?   A 10' iron or steel pole in concrete is a really darn good ground.
    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 ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • NBDrancher
    NBDrancher Registered Users Posts: 19 ✭✭
    #3
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    12’ pole, 4 feet in concrete. The other is a 10’ pole, 42” in concrete. I guess you answered my question Mike. 

    Outback VFX3524 inverter, Xantrex C-40 charge controller, Iota 24 volt charger, Siemens panels, German Solar panels, Pre-Formed Products pole mounts, Deka 6 volt batteries, 21kw Perkins/Borg Warner diesel generator.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
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    Maybe,   You need 10' of pole down into the concrete.  The metal & concrete create a very efficient ground.   The big lump of concrete is much better than 42" of concrete


    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 ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • NBDrancher
    NBDrancher Registered Users Posts: 19 ✭✭
    #5
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    I will be installing a 8' copper-clad ground rod beside my first array.  Digging a 10' hole in the caliche here at the ranch would be tough. 
     
    Outback VFX3524 inverter, Xantrex C-40 charge controller, Iota 24 volt charger, Siemens panels, German Solar panels, Pre-Formed Products pole mounts, Deka 6 volt batteries, 21kw Perkins/Borg Warner diesel generator.
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  • andtime
    andtime Registered Users Posts: 8 ✭✭
    #6
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    Wow, great info! On a similar track, I have my four 100w panels on a small wood frame rack sitting in concrete deck blocks. I am not using metal rails--just wood--so panels are not joined together at all. Soil is very rocky, not sure I can drive a rod very far. Any ideas for how I can ground? some kind of jumper between the panels' frames, and then a rod driven only a foot or so into the ground--would that be better than nothing?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,440 admin
    #7
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    Do you have a chance of lightning in your area (one good reason for ground solar panel frames)?

    If you want to ground (with 6 AWG bare wire from panel to panel to ground rod/plate):

    https://www.solar-electric.com/gbdbtsopagrl.html

    The idea is that you do not cut the 6 AWG--You just drop it into the "slot" and tighten the binding screw.

    For grounding, some folks have rented a hammer drill and driven a ground rod into the earth:

    You can find ground rod driving adapters (and some folks have driven by placing the hammer drill over the rod):

    https://www.amazon.com/Bosch-HS1924-Ground-Rod-Adapter/dp/B0009H5POU

    And if not possible to drive an 8 foot rod--Burying a 12 inch square plate 30" deep can work too (or whatever your code requires for ground plate/ground rod options):

    https://www.harger.com/product/ground-plate-assemblies
    https://www.hunker.com/12445983/how-to-install-an-electric-ground-plate

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • andtime
    andtime Registered Users Posts: 8 ✭✭
    #8
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    BB. said:
    Do you have a chance of lightning in your area (one good reason for ground solar panel frames)?

    If you want to ground (with 6 AWG bare wire from panel to panel to ground rod/plate):

    https://www.solar-electric.com/gbdbtsopagrl.html

    The idea is that you do not cut the 6 AWG--You just drop it into the "slot" and tighten the binding screw.

    For grounding, some folks have rented a hammer drill and driven a ground rod into the earth:

    You can find ground rod driving adapters (and some folks have driven by placing the hammer drill over the rod):

    https://www.amazon.com/Bosch-HS1924-Ground-Rod-Adapter/dp/B0009H5POU

    And if not possible to drive an 8 foot rod--Burying a 12 inch square plate 30" deep can work too (or whatever your code requires for ground plate/ground rod options):

    https://www.harger.com/product/ground-plate-assemblies
    https://www.hunker.com/12445983/how-to-install-an-electric-ground-plate

    -Bill
    Thanks, Bill! No more lightning activity than normal, I guess--Northern MN. Thanks for the adapter pic, I can handle that. Hadn't heard of the square plate, I will definitely look into that. Soil is more rock than anything, hence, I'm worried about driving anything very deep without hitting ledge rock. 

    SO appreciate the links---thank you!
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