Grounding XW MPPT

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Hi all,enjoyed the forum so far, I have a question regarding a Xantrex XW MPPT controller on my 1.1KW off-grid system.
I have a grounding conductor wired directly from the panels to one lug of the GFI Ground terminal on the controller, on the other lug is a conductor going directly to the ground rod. The book for this states "there can be no other neutral to ground connections in the system'.... does this apply to the AC side as well?
I have a Xantrex DR2424 inverter wired to the AC distribution panel, does the neutral/ground bar in the AC panel need to go direct to a separate ground rod?
Thanks in advance,

Greg

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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
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    Re: Grounding XW MPPT

    Yes, I have all the grounds, negative of DC, panels frames, neutral of AC bonded to a single ground rod at the house.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,493 admin
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    Re: Grounding XW MPPT

    If you have a link to the manual/page you are talking about -- it would help.

    From a controller point of view--you do not want to "share" the solar panel ground because (I assume) that this is the "Ground Fault" sense wire too (goes through a fuse or circuit breaker... If more that X amps flows, the fuse/breaker opens and "faults" the controller.

    If this is the DC ground on the "battery side" of the controller... You can send this wire to the ground rod--and use the same ground rod to connect to the "neutral bond" in your AC distribution panel.

    Normally, the "neutral bond" occurs only at one point in the system to prevent "ground loops" (your return current going through the "green safety wire" instead of the white "neutral" wire).

    Because "Neutral" generally applies only to the AC wiring for a North American Home (120/240 VAC split phase typical home panel)--I am not sure how it has anything to do with the "DC Side" of the charge controller.

    Lastly, not all inverters can operate with a ground neutral (especially if the negative battery terminal is also grounded)... Check the manual (or with the inverter manufacturer) to see if Neutral bonding is supported/required or not... Doing this wrong can give you some nice smoke effects and flashing of light (not a good thing).

    Typically, TSW (True Sine Wave) inverters support neutral bonding... And MSW (Modified Square/Sine Wave) inverters do not.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,801 ✭✭✭✭✭✭
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    Re: Grounding XW MPPT

    As Bill said in a detailed way... Your AC neutral must be bonded in one place (main panel) and has nothing to do with the charge controller on the DC side. The AC side can have it's own ground rod or UFER or it can use the DC system ground. They all need to be sized correctly if shared.

    Also the Xantrex or Trace MSW inv/chg is not like a cheap MSW inverter and can be used in a neutral bonded home.

    The OP is making a normal mix-up of DC side and AC side. For his XWCC he just needs to be sure that the negative battery terminal is not connected anywhere to ground as the XWCC will use this for GFI.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • System2
    System2 Posts: 6,290 admin
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    Re: Grounding XW MPPT

    Thanks for setting me straight on that one! I think I've got it now.
    There is something else I've been a little confused about regarding the grounding procedure, and that is most of what I've read says to use 'a conductor sized to the largest conductor in the system'.... well to me that would be the 2/0 battery to inverter conductors... is that the size of ground wire required? As of now, I have the XWCC grounded with #6AWG.
    Really appreciate the help so far. This is the best and most informative renewable energy forum I've found so far. I'm mostly self-taught on this stuff, not neccesarily by choice, but because good info has been pretty hard to come by out here in southern illinois! There are very few installers in this area as of yet.
    I've been 'getting by' on 210watts of solar for about 4 years now...just now upgraded to 1KW...:D