EV charging from solar — is it practical?

The real question is whether your battery survives the experience, not whether the sun does — and @BayTim's spot on about state of charge being critical. I've got a modest 5kWh LiFePO4 backing my shepherd's hut setup, and I learned the hard way that charging a car from solar is basically asking your battery to do a second job it didn't apply for.

Your 8kW sounds decent on paper, but EV chargers are greedy little blighters — they'll happily drain a battery faster than you can say "winter solstice" if you're not careful. You'd likely need proper battery-to-charger management (Victron's DC charger is brilliant but pricey) or accept that you're only really charging when there's genuine excess solar and your home batteries are happy.

What's your actual battery size? That's the conversation that matters.

Yeah @BayTim's hit the nail on the head — you'll basically be choosing between keeping your lights on and charging the motor, which is a laugh when you think about it.

8kW sounds decent until you realise a Tesla Wallbox wants 7.4kW continuous and you've just nuked your battery headroom. I've got a static caravan with 4kW panels and a measly 10kWh LiFePO₄ — charging anything bigger than a milk float means either waiting for a sun-soaked summer's day or accepting that the inverter's going to have an aneurysm.

The honest answer: it's practical if you've got spare capacity after your house loads are sorted, which most of us haven't. You'd be better off waiting for peak generation hours and only topping up then, or just accepting the grid's going to have to do the heavy lifting. Your battery will thank you for it.

I'll be honest, this is what killed the idea for me on the narrowboat. Had 4kW of panels and a decent battery bank, but the moment you start pulling 7-10kW for an EV charger, you're not just draining the battery — you're fighting the inverter limits and thermal stress.

The math looks brilliant on a sunny July afternoon. The reality? Most people's daily charge window is either early morning (clouds, low angle) or evening (no sun at all). You end up either:

1. Charging during peak generation and accepting wildly variable charge rates that confuse the car's BMS
2. Exporting to grid anyway and just using AC charging like everyone else
3. Over-specifying battery capacity to the point where the capex makes grid charging look sensible

Where it does work is if you've got genuine surplus solar on your generation curve — the stuff you're currently dumping or exporting. That's the honest question to ask yourself: after your house loads and battery management, what's actually left over most days?

@CableTieWarrior, what's your typical daytime surplus looking like

I've wrestled with this exact problem on the narrowboat, and it's more nuanced than folks are making out. The issue isn't really whether it's practical — it's whether you're willing to accept the constraints.

Thing is, you're not actually charging the car from solar directly in most setups. You're charging it from your battery bank when there's surplus, which means your 8kW panel array needs to simultaneously keep your house running and fill a battery big enough to store meaningful charge for the car. That's a tall order even in summer.

What changed my thinking was accepting that I'd only ever add 5–10 miles of range on a decent day, and only when everything else was already sorted. If you're genuinely off-grid and your priorities are lighting, heating, essentials, then EV charging becomes the "nice to have" that gets sacrificed first.

If you're grid-connected though? Different ballgame entirely. Your Victron can export excess to the grid and import cheap rate leccy when needed. That's where the economics actually stack up.

What's your grid situation?

The real bottleneck isn't the solar generation—it's your battery bank and charge controller capacity. I'm running 6kW on the van with a 400Ah LiFePO4 setup, and I can shift decent charge rates into my leisure battery, but that's nothing compared to what an EV demands.

On a narrowboat, I learned the hard way that you need to think about when you're actually generating versus when you need to charge. Summer's brilliant—I could theoretically top up an EV battery most days. Winter? You're looking at maybe 30% of your nominal output on a grey day.

@CableTieWarrior, your real constraint is whether you want to size your battery bank large enough to buffer the excess solar and then discharge it into the EV. That's expensive. Otherwise you're effectively diverting solar that could keep your house running.

What's your current battery capacity and what vehicle are we talking about? That'll determine whether it's sensible or whether you're better off just running the grid charger when the sun's doing its thing and using solar for everything else.

8kW sounds decent on paper but you'll find yourself charging the motor at 2am when the sun's having a laugh, mate. The real question is whether your battery bank can handle the throughput—most home setups choke trying to simultaneously run the house and push 7kW into an EV.

I've got a similar headache with my static caravan setup: 6kW panels feeding batteries that'd rather service the garden office than charge my partner's Leaf. The Victron gear helps you see exactly where the bottleneck is (usually your charge controller or battery discharge rate), but knowledge doesn't magically create free electrons.

If you're serious about it, budget for either a meaty battery bank upgrade or accept that summer months you'll get meaningful solar charging and winter you'll be back on grid. The hybrid route—solar tops up your batteries, grid handles the EV charging demand—works but rather defeats the point, doesn't it?

What's your battery capacity sitting at currently?

Running an EV charger properly off-grid needs honest thinking about your duty cycle. 8kW solar sounds good but winter generation is genuinely rough—you'll be looking at maybe 2-3kW on a decent December day.

The real question is whether you've got battery capacity to match. If you're trying to top up an EV daily plus powering the house, you'll need serious storage. I'm talking 20-30kWh minimum, ideally more. A single 7kW charger can drain a modest battery bank in under an hour flat.

Victron's MPPT controllers are solid, but have you factored in charging losses? DC-to-AC conversion (inverter), then AC-to-DC again (car charger) is pretty inefficient overall.

Honest answer: works better as a "charge when conditions allow" setup rather than daily reliance. I've seen people install 22kW chargers on off-grid systems then complain they're constantly running the generator.

What's your current battery capacity and winter usage pattern like? That'll tell you if it's workable or if you're looking at a gen-top-up situation.

The lads have hit the main points but here's what I'd add from my own setup: your MultiPlus is going to be the real constraint, not the solar array itself. That unit's designed for household loads, not dumping 7kW+ continuously into a car battery.

You'll need either a dedicated EV charger that can talk to your battery management system, or accept you're basically using grid power for actual charging and the solar just tops your home batteries. Most off-gridders I know with EVs do exactly that — solar charges the house bank during the day, then charge the car overnight when they've got spare capacity.

Winter's brutal too. Your 8kW might manage 2-3kW average in December, so you're looking at 15+ hour charge times realistically.

If you're serious about this, look at a Fronius Ohmpilot or similar device that can intelligently divert excess solar to the car only when your home batteries are full. Otherwise you're fighting the system design rather than working with it.

What's your battery capacity at the moment? That'll determine whether this is even worth pursuing.

@CableTieWarrior The lads are right about winter, but I'd focus on what @Spud74 mentioned — your MultiPlus becomes the bottleneck faster than you'd think.

What's your battery capacity behind that 8kW array? That's the real question. An EV charger drawing 7-11kW will drain even a decent battery bank in hours if you're not getting simultaneous solar generation. My garden office setup taught me this the hard way — looked great on a spreadsheet, utterly impractical in January.

The practical route most folks miss: size your charger to match your realistic surplus solar, not your peak capacity. Three-phase capable chargers like the Zappi let you dial this down to 1.4kW minimum, which helps enormously. You'll charge slower on marginal days but actually move electrons without flattening your batteries.

Also consider whether your MultiPlus can handle the AC coupling properly — some configurations struggle with the inrush when a charger fires up. Worth checking your exact model specs against Victron's documentation on AC loads.

What's your battery bank

Mate, the real question is your battery capacity more than the solar panels. 8kW looks decent on paper but you're fighting two battles — winter generation and charging an EV that'll want 7-11kW when it's plugged in.

What's your current battery setup? If you've got decent storage (say 15kWh+), you can time charging for peak solar or top up overnight at off-peak rates if you're grid-tied. If you're fully off-grid, you need to be ruthless about when you charge.

I'm running a Fogstar controller with about 12kW panels into 20kWh LiFePO4, and I only charge the EV during peak sun hours — May to September mostly. Winter, it stays on the grid or doesn't happen. That's the honest truth.

Your MultiPlus setup means you've got backup from the grid presumably? If so, hybrid charging (solar boost when available, grid top-up when needed) is actually quite sensible. Beats oversizing batteries you'll rarely fill.

What's your storage situation currently?

Battery capacity's the real bottleneck here, @Curly38's spot on. Your MultiPlus will happily pass through surplus solar, but you're essentially donating to the grid if your batteries can't store it first — and EV charging will absolutely drain them faster than your 8kW can replenish on grey days (which, let's be honest, this is the UK).

What matters: how much usable storage have you got? A 10kWh battery might feel decent until you try charging a Leaf and suddenly it's 2pm and everything's flat. Winter's genuinely grim — you'll be grid-dependent anyway.

Pragmatic approach would be a dumb relay setup that only lets the charger run when your batteries hit 80%+ and solar's actually producing. Saves faffing with the MultiPlus logic. Most folk end up using cheap daytime electricity rates instead, which feels like giving up until you realise it's more reliable than waiting for the sun.

What's your battery situation looking like?

The practical answer depends entirely on your battery bank size and how you're planning to charge. If you're relying on real-time solar passthrough via your MultiPlus, you're looking at maybe 3-4kW continuous on a decent day — that's roughly 1-2 hours of charging for a typical EV, not really viable for daily use.

What actually works is treating your battery as the intermediary. Charge the battery from solar during the day, then feed the EV overnight or during poor weather. This requires honest sizing though — most people underestimate winter output. I've got 6kW across my boat setup, and in December I'm getting perhaps 800W peak. Your 8kW will be similar at best.

Real consideration: does your current battery capacity support both your existing loads and EVs? If you're already cycling deeply most days, adding an EV just means investing in significantly more storage. A 10kWh usable battery makes this properly viable; anything less and you're running the numbers hopefully rather than practically.

Also factor in that most EVs charge inefficiently below 10% battery state of charge — the Multi

@CableTieWarrior Battery size is definitely the limiting factor here, but there's another angle worth considering — what's your actual usage pattern like?

I've got a similar setup with a garden office and I initially thought EV charging would be straightforward. The reality is you need to time it properly. Charging during peak solar hours (10-2ish) works reasonably well, but once you're into autumn and winter, you're basically relying on battery discharge.

A few practical considerations:

• Load shifting matters — Can you charge mainly in summer months, or do you need year-round capability?
• Charger specs — Even a modest 3.7kW home charger can hammer a battery bank if you're not careful. A Victron Energy management system can help regulate this.
• Grid backup — Are you grid-connected? That changes everything. You can offset your charging costs through export.

What's your battery capacity currently? That'll determine whether this is genuinely practical or whether you'd be better off running grid-assisted charging and using surplus solar to offset consumption elsewhere (heating, etc.).

The real question is what your actual daily surplus looks like. 8kW sounds decent but peak solar rarely lines up with when you need to charge the car.

I've got a similar setup and honestly, it's more about timing than total capacity. Summer I can easily top up during the day if I'm home and the battery's already charged. Winter? Forget it — barely covers the house.

What actually works better is treating it as opportunistic rather than primary charging. Use grid when you need reliability, soak up surplus when conditions are good. That way you're not oversizing batteries just for occasional EV top-ups.

Battery chemistry matters too. LiFePO₄ handles the variable charge rates from solar better than lead-acid. If you're already running Victron gear you've got solid monitoring at least — can see exactly what surplus you've actually got to play with.

What's your current battery bank looking like?

The elephant in the room that nobody's mentioned yet is the charge rate limitation. Even if you've got surplus solar, most domestic EV chargers pull 7-11kW continuously. That's not a peak figure—that's sustained demand. Your 8kW array might generate that in ideal conditions, but you're fighting cloud cover, angle losses, and seasonal variation.

What's worked for my setup (8.5kW on the boat, though granted that's smaller scale) is accepting that solar-only EV charging means slow top-ups on genuinely sunny days, not rapid charging. If you're commuting daily, you'll need either a substantial battery bank to store midday surplus, or you're accepting grid charging for the bulk of it.

The Victron system gives you flexibility though—you could configure it to pull surplus to the EV charger only when battery state of charge hits a certain threshold. Stops you hammering the grid at peak times whilst keeping the car topped up.

Real question for @CableTieWarrior: what's your battery bank size currently, and what's your actual daily kWh surplus after household consumption? That'll