Ground connection for EG4 6000XP and solar panel chassis in an off-grid setup

Grounding on a mobile or off-grid build always seems to spark more confusion than it should, and I've been through this exact headache on both my narrowboat and the van conversion I did a few years back.

For the EG4 6000XP specifically, the chassis ground on the inverter/charger needs a solid, direct run to your main negative busbar — don't daisy-chain it through other kit. Decent gauge cable too, I used 16mm² on mine and wouldn't go lighter.

For the panel frames, the question is really where your setup lives. On my boat, I bonded all the aluminium frame rails together with a dedicated earth wire and ran that back to the same busbar. Common earth point — everything referenced together. If your panels are on a ground-mounted array rather than a vehicle or vessel, you'll want to look at whether a ground rod is appropriate too, particularly for lightning dissipation.

The bit that catches people out is bonding the negative DC rail versus the chassis/frame ground — they're related but not the same conversation. Keep them clean and intentional rather than letting them accidentally commingle somewhere they shouldn't.

Has anyone had issues with the EG4 specifically throwing ground fault errors when panel frames aren't properly bonded?

Genuinely curious, because I've seen some threads on the US forums about this but nothing much from UK installs. Fogstar and Victron kit tends to be better documented for our setups but the EG4 is creeping in more now.

Would love to hear what others have done, especially anyone running this on a static tiny house or cabin build where NEC/Part P complications come into play.

@WezFisher — narrowboat grounding is its own special rabbit hole, I can tell you that much.

On the boat I ended up running a dedicated copper earth bar bonded to the panel frames, then a single clean run back to the negative busbar. The EG4 chassis earth goes the same route — no daisy-chaining frames together and hoping for the best.

The bit people miss is isolating the AC earth from the DC negative unless you've got a specific reason to bond them. On a floating vessel especially, mixing those up invites galvanic corrosion that'll quietly eat your through-hulls.

One thing worth checking: is your EG4 in a truly isolated off-grid config, or are you occasionally connecting shore power? That changes the picture considerably for how you handle the neutral-earth relationship.

@WezFisher the shepherd's hut I wired up taught me a lot about this. Running a separate equipment grounding conductor back to a single point earth rather than daisy-chaining chassis grounds was the turning point for me — stopped all sorts of phantom readings on my Victron MPPT.

One thing worth noting for the EG4 6000XP specifically: the panel chassis ground and the inverter ground really want to meet at the same busbar, not at different points along a chain. I ran 6mm² green/yellow back to a copper earth bar and it cleaned everything up considerably.

The EG4's manual is a bit vague on this for non-US installs, so don't take it as gospel for a UK build.

Really useful thread this. One thing I'd add — with the EG4 6000XP specifically, don't neglect bonding the panel chassis to your equipment ground at the array itself rather than relying on the mounting structure alone. Even on a static off-grid build, resistance through bolted aluminium joints can be surprisingly high over time with weathering.

I ran a dedicated 6mm² green/yellow back to my earth busbar from the frame, separate to the DC negative, and it made a measurable difference when I checked continuity later. Also worth confirming whether your particular setup calls for a TN-S or TT earthing arrangement — off-grid systems often default to TT with a local earth rod, which changes how you approach the whole thing. @IslandOffGrid's point about a separate EGC is spot on for that reason.

@Barry1962 good point on the panel chassis bonding — can I ask what gauge conductor you used for that bond back to your earth point? I've seen people use anything from 4mm² to 10mm² and I'm not entirely clear on what the correct sizing methodology is for a non-current-carrying protective earth in a DC system.

On my narrowboat setup I followed BS EN 60092 for the bonding runs, but a static garden office install presumably falls under different regs entirely — possibly BS 7671 Amendment 3?

Curious whether anyone has had an NICEIC or NAPIT inspector actually sign off an EG4-based system and what they said about the earthing arrangement specifically. The EG4 documentation feels like it's written primarily with NEC (US) requirements in mind, which doesn't translate cleanly to a UK installation.