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Thread: Main to Inverter and Inverter to Load Wire Sizing

  1. #1
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    Main to Inverter and Inverter to Load Wire Sizing

    Hey fellas, long time lurker, finally decided to make an account. Got a bit of a situation on a solar install I'm quoting for a customer.

    The setup is two inverters, 4kw and 8kw in parallel, 60ft from the 200A main load center. Non essential circuits will be kept in the main load center, and essentials will be moved into a 200A sub panel right next to the main.

    Each inverter has a maximum surge pass through of 50A and is protected as such at a load center mounted under them. So a maximum potential of 100A coming from the main load center to the inverters, and a maximum potential of 100A going back to the backup sub panel.

    Due to the design of the house, it would be virtually impossible to get conduit to the main or backup panels. There is a partial 4ft tall crawlspace however. The best I can come up with would be a run of 2/2/2 AL SER and one of 2/2 AL SEU from the panels through the crawlspace, attached to the bottom of the floor joists. Then splice to XHHW AL in a trough and continue the rest of the way outside in conduit along the bottom edge of an exterior wall, up and into the inverter load panel.

    I believe I need a total of 5 current carrying conductors, plus ground;

    L1 & L2 from the main to inverters, L1 & L2 from the inverters to backup panel, then a shared neutral.


    First question, how does this plan sound, code wise? I'm in an area that doesn't require inspection's and has no official NEC cycle to follow but I prefer to keep things in line with 2014 at least.

    Second, what size would the cable need to be sized? 1awg or would 2awg AL be suitable?

    Thanks in advance!

  2. #2
    Join Date
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    How are you sharing the neutral? The MSP and essential load panel will not be interconnected except through the inverters. So you would need a neutral from the MSP to the inverters and inverters to the essential load panel, right?

  3. #3
    Join Date
    May 2011
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    I'm with pv_noob, I think you need a neutral both ways.

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