I’m planning a grid-connected ESS solar installation and I have most of it figured out except the grounding and Earth connections. After consuming many conflicting articles and videos, and reading Victron’s excellent book Wiring Unlimited, this is what I’ve come up with. Is there anything obviously wrong with this setup, especially when it comes to grounding / Earthing?
Thanks!
The RS range of products, by hardware design, are completely isolating (galvanic) the battery from the AC side.
This means that the battery and all of its internals are floating.
Why on earth would want someone to ground the battery DC minus and bring a (potential/accidental) dangerous wire on the DC side of the battery?
When I am saying potential dangerous wire I am referring the situation when the house’s main earth connection (second T, as you say) fails.
I don’t have an answer for you but some comments for you to consider. My grounding is very similar but I have a quattro for the inverter:
F.
I see your point. Does the same apply to the classic quattro?
Thanks for your answer Alex!
It is confusing. This is from Wiring Unlimited (at the very end of section 7.7):
The ground busbar connects all the chassis, the AC loads, the Earth wire from the grid, and the battery negative.
Hey Fideri,
It’s confusing isn’t it? Grounding the battery negative can be recommended or frowned upon, the same with mixing AC and DC grounds. I’ll check what you say about grounding the panels.
Thanks!
Hi Hamilton
Best practice for us is usually to give the PV installation its own earth pegs with their own surge protection etc. Since the reason they dont want you to use the same ground at the board is to prevent a lightning surge running through the panels into your system or if there is leakage to the frame from the panels, to prevent that voltage coming into your system if surge protection were to fail.
Yes, indeed, but that inverter is a little bit different in hardware topology than the Multi RS.
I, for one, have the same system as you (Multi RS) and, like you, grounded that batteries case, but not the DC negative.
Again, starting from the assumption that DC and AC are totally separated in the RS range of products (as advertised by Victron in one of their videos), I don’t see the point of bringing something from “the other side” onto the battery side.
LE:
Also on Multiplus could be said that the AC part is completely separated from DC side, but in the end, it could depend on your legislation.
Anyway, with the speed the technology evolves, it could easily surpass any legislation already in place and we could easily fall victims of habit… 
LE2:
I was thinking like this… If a live wire from AC side will accidentally touch any battery terminals/busbars and I have the grounding point connected to the DC negative, then a big bang will happen. If I will leave the DC negative not connected to the grounding point, as the DC side is floating, then no big bang will happen if an AC live will accidentally touch any battery terminals/busbars.
Hey Alex, it makes sense to keep things separated. And I don’t want a big bang! For now I’ll ground the chassis of the Multi and batteries and leave the DC floating. Also, the Pylontech manual doesn’t say anything about grounding the negative. I’ll also check with local installers, they should be up to date with local regulations.
Thanks for taking the time!
Nice schematic, well done. Instead of 2 changeover switches. I often move the MCB closer to ACin and do a locked MCB between housemeter and AC panel.
This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.
