andy300zandy300z Solar Expert Posts: 39
Hello guys i have a couple of questions in regard to a proper ground.

1. Do i have to ground my batteries to an earth ground ?

2. Can i ground my Inverter (110 AC Line out) , Batteries and charge controller to
one point of contact an then direct it to a 6ft Copper Earth Ground?



  • BB.BB. Super Moderators, Administrators Posts: 33,313 admin
    Re: Ground

    The Battery / Inverter system does not need earth grounding for normal operations...

    Generally, grounding is for safety/abnormal conditions... For example, Lightning (want all metal inside the home/cabin to be at the same potential--that way, people inside should not get shocked by touching a mixer and the sink), High Voltage line crosses (if this was grid power), preventing energizing one section of metal (say gas pipe) while cold water pipe is grounded (get a shock between stove and sink), etc.

    Grounding a DC Battery bank is common in fixed applications. Generally drive a ground rod next to the building and run one 6 awg or larger wire from battery negative ground to ground rod. Run other safety grounds directly to the ground rod and make sure you don't have "Ground Loops" (say you negative ground at the bank, and negative ground at a ham radio--DC return current has a choice between the negative lead to the battery or through the safety ground--which you do not want to carry normal loads).

    Grounding AC inverter output... No one answer here... First check the installation/user manual for ground instructions. Usually the metal case would be connected to your earth ground (if the metal shell is not tied to the Negative Terminal--again another chance for creating ground loops if you are not sure).

    Grounding the AC output to create a Hot/Grounded Neutral setup--Generally this can be done with True Sine Wave inverters and generally cannot be done with MSW inverters. Always read the manuals before wiring.

    TSW inverters--You have the option of creating a grounded neutral or not... For small systems, not grounding the neutral is probably the usual setup.

    For larger systems, Neutral bonding follows the electric code... But gets into issues with AC generators... Generally smaller genets have floating AC outputs. And larger gensets have grounded neutrals... Because you don't want ground loops--Generally you either have to lift the neutral bonding in the genset or use an AC tranfer switch that also switches the Neutral leg.

    For MSW inverters, generally, there is no electrical isolation between the DC input and AC output. If you safety ground the DC input and do "Neutral Bonding" on the AC output--you will create a short across the inverter and probably ruin the inverter.

    It may be easier to discuss your exact setup (brand/model/setup) regarding grounding rather than talking in generalities. There are just too many variables.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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