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Grounding question - two strings on separate roof planes

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  • Grounding question - two strings on separate roof planes

    Grounding question - two strings on separate roof planes

    Located in Oregon. Just wrapping up our DIY solar install and have a question about grounding.

    System info:
    SE-7600H-US
    40 Hyundai 305w panels (290 STC)

    I have 2 strings, one is east facing and the other is west facing. Under each string I have a SolaDeck junction box. From each SolaDeck I have 3/4" EMT which runs to a single double gang box in the attic. From this box I have a single 3/4" EMT running to the inverter. I have 6 AWG bare copper coming from the racking equipment into each SolaDeck. My original plan called for #6 to come off the roof, combine somewhere and then run to the building UFER. Now I'm reading my ground needs to be continuous... I don't want to run two separate #6 grounds and I don't want to run a #6 ground up and over the ridge (connecting the two racks together). So, after doing some reading, I'm thinking maybe I could run two separate 10 or 12 AWG THHN ground wires all the way back to the service panel? I'm thinking I would also need to bond one of these to the EMT along the way? I'm not sure this would pass due to lack of lightning protection? I really want to avoid having the ground wire exposed on the outside of the house.

    I plan on grounding the AC side of the SolarEdge separate from equipment ground on the roof.

    Any thoughts or suggestions? I have a call into the inspector, but it's hard to get in touch and I need to wrap this up while I have help.

  • #2
    I think you are allowed to use a non-reversable crimp to connect ground wires. Check with someone local in your area.
    Powerfab top of pole PV mount (2) | 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

    Comment


    • #3
      Originally posted by Mike90250 View Post
      I think you are allowed to use a non-reversable crimp to connect ground wires. Check with someone local in your area.
      I think I follow you and I think I have seen reference to something like this. I’m not sure where 6AWG came from as I don’t think that size is truly needed for grounding the racking, guessing it has to do with lightning?

      Comment


      • #4
        It's for Lightning, you don't want to guide the strike into your house power center, guide it with lazy bends, to the ground rod, no sharp corners
        Powerfab top of pole PV mount (2) | 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

        Comment


        • #5
          You can use irreversible crimp connections, and it is still considered continuous.
          6AWG is required under the array to prevent damage. Any where a ground wire may be subject to damage it must be at least 6AWG. If you are running it in the conduit along with the array wires, you can likely downsize to the same size as the array wires (as long as you use crimp connections).

          On my SolarEdge system, the ground comes into the combiner as #6 solid, then splices to #10 stranded. That wire then goes to the inverter ground. Then I just have 8/3 NM-B (romex) from the inverter to the main panel.

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