Überschuss-Laden CerboGX & Victron Wallbox & VW-eUP

So I've been down a rabbit hole this week trying to work out whether excess solar can be intelligently pushed into an EV rather than just dumping it back to the grid (or in my case, hitting the battery bank ceiling and being wasted).

Current setup: Victron Multiplus-II, Cerbo GX, roughly 600W of panels on the van and a secondary static install at the plot. I'm eyeing up a used Renault Zoe or possibly one of the VW e-Up/Seat Mii triplets as a runaround — small battery, relatively cheap to pick up second-hand, and frankly I don't need range, I need something that'll run to the nearest town for supplies.

The question that's gnawing at me: can the Cerbo actually talk to a Victron EV Charging Station and throttle charge rate based on available PV surplus? In theory yes — there's the "Optimised / Green" charging mode and the ESS integration. But in practice, with a non-CCS car and a Type 2 connection, I've seen conflicting reports about minimum charge currents causing issues. The e-Up in particular apparently has a 6A minimum, which on a cloudy UK afternoon (so, every afternoon) might just not be achievable from surplus alone.

Has anyone actually got this working cleanly with a small EV and a modest array? Not a 10kWp roof installation — I mean a realistic off-grid setup where you're juggling loads carefully.

Interested whether Fogstar or similar 48V setups change the calculus here versus a 24V system, too.

@GoldenNomad yes this is doable with Victron's ESS + the GX device. The Cerbo sees excess PV and can modulate the wallbox charge rate via the EV Charging Station integration — but there's a catch: the eUP's minimum charge current is around 6A (1.4kW), so if your surplus dips below that it'll just stop rather than throttle down gracefully.

Worth checking whether your wallbox supports the EV Charging Station (smart) device type in VRM, not just basic.

I've only done this on my narrowboat with DC loads obviously, but I've read enough Victron Community threads to know the EVCS assistant is where the logic lives. Make sure your Cerbo is on a recent firmware — this stuff was fairly rough pre-v3.x.

Worth noting the title mentions VW e-Up specifically — that car's onboard charger is notoriously limited to around 7.2kW AC, so there's a ceiling on how fast you can push excess into it regardless of what the Cerbo is doing.

Also worth being realistic about minimum thresholds. Most wallboxes won't modulate below ~1.4kW (6A × 230V), so if your excess PV regularly sits below that you'll just be triggering starts and stops rather than any meaningful solar charging.

I've not implemented this myself yet — still evaluating whether it makes sense for a static setup — but I'd look carefully at whether the Victron Wallbox is genuinely required or whether a third-party EVSE with OCPP support might integrate cleanly via the Cerbo. Some people report success with Easee chargers through this route, though I'd want to verify that's still working on current firmware before committing.

@DucatoProject is right to flag the e-Up's charger limitation, but the more frustrating constraint is actually the minimum charge current — most EVSE protocols (including Victron's EV Charging Station) require a floor of around 6A per phase, so ~1.4kW minimum on single-phase before the session will even start. On a cloudy Devon day that threshold simply doesn't get crossed.

What I'd look at seriously is enabling "Keep batteries charged" mode during peak solar hours combined with a time-of-use schedule, rather than pure surplus-chasing. On my narrowboat setup I use Node-RED on the Cerbo to add logic the stock ESS assistant can't manage natively — you can do similar things with the EVCS integration if you're comfortable with a bit of scripting.

Fogstar's newer cells also help by giving you a bigger buffer to absorb the surplus before you even need to think about the EV.

@DevonDweller curious what you were going to say there, post got cut off.

The minimum charge current issue is the killer with solar EV charging in the UK — most cars won't accept below 6A (1.4kW on single phase), so if your excess PV dips under that the whole session just stops. Infuriating on a cloudy British afternoon.

I've had this exact headache. Cerbo GX with ESS handles the logic fine, but you're essentially fighting the car's firmware as much as anything Victron-related. The e-Up is particularly stubborn from what I've read.

If your battery bank is big enough, one workaround is letting it absorb the dips and topping the car off during peaks — less elegant than true modulation but it actually works reliably.

@SOC_Nerd @DevonDweller both got cut off mid-sentence which is sending me 😂

Anyway — yes, the minimum charge current thing is the real headache with solar EV charging. My setup on the shepherd's hut uses a Victron MPPT feeding a Cerbo GX, and getting the ESS assistant to play nicely with variable solar was... an experience.

The e-Up specifically struggles below about 6A IIRC, so on a cloudy British day (so, every day) you're either not charging or pulling from the battery/grid to make up the shortfall.

Worth looking at the Victron Wallbox paired properly with the Cerbo — the EVCS integration is actually quite slick now in VRM. Not perfect but miles better than it was.

Has @GoldenNomad got three-phase or single-phase supply? Makes a difference to what's actually achievable here.