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System check and grounding, Skoolie with ground array

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  • System check and grounding, Skoolie with ground array

    I am setting up a system for a Skoolie (RV) that will be strictly of grid. There is no option for grid connection. I purchased it from someone and I am making renovations while also trying to use some items it came with. We will not be moving often. It will likely stay in one spot for a year or two at a time at least.I am nearly ready to begin solar install and need a sanity check. Here are the components:
    - 8 x 270 watt Hyundai panels (2160 watts nominal, 2 strings of 4, 152.8 Voc, 125.6 Vmp)
    - Midnite Classic 200 + Shunt + Whizbang
    - 48 battery bank (4 x 140Ah AGM. I found decent used ones for a very good price, plan to use these as starting out batteries, and upgrade to a new larger bank later)
    - Outback GTFX3048
    - 1600/2000 watt inverter generator (plan to be able to plug it in the inverter AC input in no sell mode ect and run it as needed to fill in)
    - 12V 200Ah battery
    - RV style epanel AC/DC distribution panel with 12v charger built in (NOTE: This and the 12V "house" battery came with the bus and I'd like to try to make use of them and move some 12v constant loads to it such as LED lights, compost toilet fan, roof fan, some chargers ect).

    Basic system flow as I envision it:
    Panels-->Combiner Box(installed by panels, 15A breakers)--(60-70 ft run, 10ga)-->charge controller--(4ga)-->80amp breaker-->48V battery (125A post fuse) --(1/0 ga) --> 125A breaker --->Inverter --input breaker(30A) --> AC/DC distribution panel w/ built in 12V charger--->12V 200Ah battery for the DC loads in the epanel (i realize this is not particularly efficient to run through the inverter and then back to DC for the 12v, but just trying to find a way to use some of what I have already).

    Due to the spot I have my best sun exposure is actually going to be putting the panels about 50-60 feet away from the bus on the ground.In the future I may want to roof mount the panels if we ever move the bus to a better spot for sun. I have been reading a lot of posts here and have seen the diagrams from Sunking which show grounded vs ungrounded systems, and also his recent one which shows a grounded "trailer" diagram. These has been helpful and it seems clear I am going for a "grounded" system, that is tying ground to chassis frame at a common point. But what is less clear is whether I should be putting in an earth ground rod, and how my external ground mount panels affect that.

    1) In the bus where I have most parts I would tie my charge controller ground connector, inverter ground connector, AC panel ground bar, 48 batt neg, 12V battery neg, all to a common ground bus bar....and in turn tie that to the chassis. Typically this would not carry any current EXCEPT for the 12V battery will have for example house lights and some fans negative through bus chassis. If I have that correct what gauge wire for the final tie to the bus chassis? My thinking is it should be sized for worst case fault current which would be 48volt battery somehow shorting to chassis (125a fuse, so 1/0 ga like my other wires)
    2) What about the external ground array? Should those have the panels grounding wire separately connected to an earth grounding rod out by the array? This would be my assumption...and would seem only needed for lightning.
    3) Would I be ALSO taking my bus chassis ground point and tying that to an earth ground rod I put in near the bus?
    4) Given that I have no grid connection with an upstream neutral-ground bond, and my generator does not have neutral-ground bond....would I be making my own AC neutral to ground bond in the AC distribution panel? Do I even need this?
    5) What about when I move the panels up to the bus roof someday? have the panels ground wire then come down to combiner which would be in the bus with everything else and tie it in to the common ground bus with everything mentioned above?

    Thanks for any help!
    -Chris B.-



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