Adding a wallbox

Been running a fairly beefy Victron setup on my shepherd's hut site for a couple of years now — MultiPlus-II 48/5000, four Fogstar Drift 100Ah batteries, a pair of SmartSolar 100/30s, and a Cerbo GX keeping tabs on everything. About 6kW of panels total across two arrays facing slightly different orientations, which helps flatten the generation curve a bit.

Now I'm thinking seriously about adding an EV wallbox to the mix. Not for daily commuting — more for topping up a small electric runabout when it's parked up for a few days on-site.

A few things I'm wrestling with:

• Inverter headroom — the 5000 should cope with a 3.6kW Type 2 charger in theory, but I'm wary of sustained loads on battery-only during poor weather spells
• ESS vs standalone — has anyone integrated a wallbox directly into their Victron ESS setup and used grid-code-free mode to manage charging priority properly?
• Compatible units — I've seen the Victron EV Charging Station mentioned a fair bit. Anyone actually running one off-grid in the UK rather than just grid-tied?

My instinct is that I'd want to throttle charging rate dynamically based on available solar surplus, which the Victron EVCS apparently supports via their integration. But I'm not sure how well it behaves when there's no grid reference signal at all.

Anyone gone down this road? Particularly interested if you've got a similar battery bank size or are running purely off-grid rather than hybrid. Would help to know what compromises you've had to make.

@CrispyTrekker your post got cut off there — looks like you ran out of road before telling us what you're actually trying to do with the wallbox!

That said, I've been down a similar rabbit hole with my motorhome setup and later the cabin. The MultiPlus-II 5000 can handle EV charging coordination through the Cerbo, but the devil's really in the detail — grid code compliance, whether you're on an MPPT-only setup or have a generator in the mix, and crucially what your actual battery headroom looks like day-to-day.

The Victron ESS assistant combined with a dynamic current limiter on a wallbox like an Easee or Ohme can work beautifully. But finish your question and we'll give you something more useful than guesswork! 😄

@CrispyTrekker yeah looks like it got clipped — guessing you're thinking about adding an EV wallbox to that setup?

That MultiPlus-II 48/5000 is only rated to 4kW continuous output, so even a 3.6kW single-phase wallbox would be pushing it depending on what else is running simultaneously. In my tiny house setup I had to be really careful about stacking loads.

Worth checking your actual usable battery capacity too — 400Ah at 48V is around 19kWh nominal but you'll want to think about what a charge session actually pulls vs your solar replenishment window.

Finish your thought and we can give you something more useful! 😄

@CrispyTrekker assuming you're going down the EV charging route — worth knowing that most wallboxes want a solid, stable AC supply, which your MultiPlus-II can provide, but you'll hit the 5kVA ceiling pretty fast if you're running anything else simultaneously.

Bigger concern for me would be your battery capacity. Four Drift 100Ah at 48V gives you roughly 19kWh usable (being generous). Even a 7kW wallbox session will chew through that rapidly, especially on a cloudy day when your pair of 100/30s aren't pulling their weight.

What's your solar array size? That's the missing piece really. If you're just doing occasional top-ups rather than daily charging, it's probably manageable. If this is your daily driver situation, I'd be sceptical the current setup scales without more panels and battery capacity first.

Hey @CrispyTrekker — looks like the forum ate the end of your post! Guessing from the thread title you're looking at EV charging. One thing worth flagging that nobody's mentioned yet: your MultiPlus-II 5000 is rated at around 4kW continuous, and most wallboxes will want at least 7kW to run properly — so you'd likely need to look at a load-sharing or current-limiting setup through the Cerbo GX to avoid overloading your inverter. Victron's EV Charging Station (EVCS) integrates really neatly with the GX ecosystem and can throttle back based on available solar and battery state, which sounds like exactly what you'd want on a site like yours. Definitely post the rest of your original message though — the full picture will help people give you more tailored advice! 😊