Charging an EV from off-grid solar — has anyone actually made it work properly?

After two years of running the house on a Victron Multiplus-II 5000 with a 15kWh Fogstar Drift battery bank, I've started wondering whether I can ditch the occasional top-up run to the local Lidl charger and just charge the Nissan Leaf from the system instead. On paper the numbers look almost workable — I'm regularly seeing 8–10kWh surplus on a decent summer day from my 6kW array.

The obvious snag is that even a slow 7kW AC charge would basically flatten my bank overnight, and I'm not sure the Multiplus can sustain that kind of continuous draw without the generator cutting in. I've read a few threads about using Victron's scheduled charging and ESS to throttle the rate down, but I've not found anyone doing this in a real UK domestic setup rather than a campervan with a 200Ah leisure battery.

Has anyone here actually done this — charging a proper road EV (not a golf buggy) directly from an off-grid or hybrid solar setup? Particularly interested in whether you've used an OCPP-capable EVSE that talks back to the inverter, or whether you're just manually dialling the charge rate down on the car side. What did your daily surplus actually need to look like before it became viable day-to-day?

WillowWalker | 847 posts

@SussexDweller Great timing on this question — I made exactly this leap about eight months ago with a similar Victron setup. The short answer is yes, but you need to be realistic about what "properly" means off-grid.

The game-changer for me was setting the EV charger as a non-critical load and using Node-RED with the Victron MQTT feed to only allow charging when battery SOC is above 85% and solar yield is genuinely surplus. Essentially the car becomes your overflow dump load.

One caveat though — summer is brilliant, winter is genuinely humbling. I've accepted the car charges slowly or not at all during a prolonged grey spell. That mental shift matters more than the technical setup honestly.

What EV have you got? Some handle irregular charging far better than others.

Midge52 | 203 posts

@SussexDweller done this with my static for about a year now. Key thing nobody mentions — schedule your charging around surplus, not convenience. I use a Zappi in eco mode which waits for genuine excess before pulling from the array. Makes a massive difference vs just plugging in and hoping.

15kWh bank is borderline honestly. Fine in summer, winter you'll be robbing your house loads. I'd want at least 20kWh before committing fully.

Also worth checking your Multiplus-II's charge current limits — mine needed a firmware tweak before the Zappi played nicely with it. Victron forums have a decent thread on this.

KentVanLifer | 1,204 posts

Something nobody's flagged yet — managed charging windows are the real game-changer here. I ran a converted Sprinter on solar for three years before moving to a fixed setup, and the discipline I learned there applies directly.

Your Victron's ESS assistant can talk to a scheduled charge controller — I use a simple Shelly plug with time-of-day logic to only pull from the car charger when the Cerbo GX reports battery SOC above 85%. Otherwise you're just robbing your house bank to top up the EV.

On cloudy Kent winters, I realistically expect maybe 40-50% of my charging needs met by solar alone. The rest I schedule around overnight rates if you've got grid connection, or accept the Lidl run @SussexDweller — there's no shame in hybrid thinking. Chasing 100% purity costs more than it saves.

SilverWarden | 412 posts

Worth adding something I haven't seen mentioned yet — your inverter's AC output frequency shifting is your friend here. Most modern EVs will throttle their onboard charger when they detect frequency drift above 50.2Hz, which is exactly what a Victron does when the batteries are getting full. Effectively gives you free, automatic demand management without any extra kit.

Practical upshot: set your EVSE to the lowest current it'll accept (6A if possible), let the Victron's ESS assistant handle the heavy lifting, and you'll find the car charges surprisingly happily on modest solar surplus without ever hammering the battery bank.

@KentVanLifer makes a fair point about charging windows — combine that approach with frequency shifting and you've got a genuinely robust system. What EVSE are you all using? I'm currently on an Easee One and the behaviour has been solid.

CliffWill | 47 posts

Really useful thread — exactly what I've been trying to figure out for my setup.

One thing I'm curious about that nobody's touched on yet: does anyone know whether the EV's onboard charger plays nicely with the Victron's grid-code settings? I've read that some vehicles get confused when they see an island network rather than true grid supply, and either refuse to charge or keep dropping the session.

Running a Multiplus-II 3000 across my cabin and garden office, so not quite at @SussexDweller's scale, but I'd potentially be doing the same thing with a small PHEV rather than a full BEV. Wondering if the lower continuous power rating creates a bottleneck before I even start worrying about solar yield matching demand.

Has anyone had to tweak the ESS assistant settings specifically to keep the vehicle happy?

DazHenderson77 | 389 posts

Tried this on the boat with a modest 400W array and a Victron SmartSolar — spoiler: the car laughed at me, the batteries wept, and I learned what "minimum charge current threshold" means the hard way. Your 15kWh Fogstar is a proper setup though, so you're in with a shout. Main thing nobody's said: check your EV actually accepts the reduced current before assuming it'll play nicely — some cars have a minimum draw floor (often 6A/1.4kW) and will just chuck an error rather than throttle down gracefully with your available solar. A Type 2 EVSE with adjustable current like the Hypervolt or Ohme lets you dial it right down, which is the missing link between "off-grid solar" and "car that actually charges."

CamperEwan | 203 posts

Garden office setup here so smaller scale than yours @SussexDweller, but I did experiment with trickle charging my van from the array during summer. Main thing I'd add — time of day matters massively. Even with decent solar, trying to charge before 10am or after 3pm in the UK means you're just hammering the battery bank rather than running off genuine generation. I now only allow charging between those windows via a simple Victron automation rule. Cuts the cycling on the Fogstar cells noticeably. Worth setting hard SOC floors too — 40% minimum before the EV charger even activates.