Grounding earth bar and DC negative busbar

DIY
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1

Hi , for an off grid stationary set up, i am confused on the grounding needs. I understand the DC negative busbar ( inverter, mppt, battery, dc loads) and the main grounding bar ( ac out, pv frame, inverter chassis) connected to earth rod .

Now main question is a): does the DC negative busbar need to be connected to the main grounding bar or leave it separate? And b) do i need to bolt the mppt chassis to this main earth bar?

Thanks!

2

This depends to an extent on your local regulations.
Ideally the Chassis of the inverter and the MPPT should be connected to the main earth bar, this gives some lightning protection. Similarly the PV module mounting frame should also be bonded to this bar.
The question as to grounding the battery negative: This is generally a smaller safety issue, and would prevent any hazardous voltage building up on the battery in the case of an insulation failure - most likely in the PV array. Should the pv array become grounded at the +ve end, and the battery ws floating, then this could assume the full array voltage. The solution is to bond the -ve busbar and the earth busbar together. This link can then be removed for testing purposes if required.

3

Hi Mike -

Many thanks. Do I understand correctly it doesnt hurt to link the neg dc busbar in any case to the earth bar ? The wiring would be minimal as it is all Close to each other.

4

Yes, this is also required in some regulations.

5

Thanks a lot!