Grounding an off-grid solar system

Discussion in 'General Electronics Chat' started by mikeflood, Sep 14, 2009.

  1. mikeflood

    Thread Starter New Member

    Sep 13, 2009
    4
    0
    I am building a small solar system to provide pressurized water and a few small loads at a vacation property. Most of the loads are DC but I intend to use a 1750W inverter to provide 110v AC for occasional use.
    1) Is it OK to bond the chassis ground of the inverter to the negative bus from the battery bank?
    2) What would any of you suggest for a grounding method for this system? I'm guessing the the best way is still to follow my local code (Ontario) and drive in two ground rods. I don't want to get a lift from the 110.
    3) Do I bond my battery negative to the ground discussed in #2 above?

    Has anyone done this yet?
     
  2. Omega blood

    New Member

    Sep 5, 2007
    7
    0
    1; don't know
    2; yes
    3; I don't think so
     
  3. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    230
    My code book is still on loan, but best is to check with your codes.

    1&2) NO. Your AC should be grounded as per code which is a seperate tie to grounding electrode, the methods being laid out in the code . Bonding of the housing should be to a grounding electrode. Seperate systems required to be grounded and thier bonding may use seperate electrodes, but those electrodes must be tied together.
    3) Depends on several factors; Voltage level <> 50 Volts, two or three wire, does it run overhead?
     
  4. mikeflood

    Thread Starter New Member

    Sep 13, 2009
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    3) The DC bus is 12 volts. I asked the question because the RV I will use as a "cottage" has the negative bonded to the frame as well as the ground for the internal 120v A/C wiring. When I plug the RV into the inverter, I will be effectively tying the 12v negative to ground anyway. Should this not be done by a firm bonding at the DC bus as well?

    The DC is supplied from a solar system in a "shed" next to where the RV will be parked. The DC does not "leave" the shed. It is used to power a pressure water system, a few lights and the "brain" of a propane water heater. The entire system including solar panels, batteries, fusing, busses, and the inverter are all contained in the "shed". This "shed" also contains a standard 3-piece bathroom with toilet, sink and shower. The inverter just provides power to a receptacle on the side of the shed where the 120V cord from the RV will be plugged in. The RV is not permanantly installed - it will be moved to this location for weekend use and brought home afterward.
     
    Last edited: Sep 15, 2009
  5. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
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    A DC 2 wire circuit < 50Vdc may be grounded. If there is lighting potential, it must be grounded.

    Normally an AC circuit is grounded ONLY at the service, however, there are exemptions for recreation vehicles under CSA. In any case, all metalic housings must be bonded to ground. I suspect that your vehicle chasis is considered a bonding conductor, to which your 12vdc common is also connected to.
     
  6. mikeflood

    Thread Starter New Member

    Sep 13, 2009
    4
    0
    Thank you.

    The only remaining question is whether the 12v negative in the "shed" needs to be also bonded to ground (since the RV has the same connection). The alternative is to leave the plus and minus 12v floating and only bond anything metallic (boxes, inverter chassis, copper pipe) to my grounding system.
     
  7. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    I'll admit I'm not completely clear on that requirement. There is a section that deals with batteries and thier storage requirement.
     
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