Has anyone used a small inverter generator as a winter backup alongside solar panels?

Been mulling this over for a few weeks now. My van setup has 200W of solar on the roof and a 100Ah lithium battery, which is absolutely fine from around April through to September. But last winter I kept hitting that horrible situation where I'd had two or three overcast days in a row, the battery was down to 20%, and I was rationing everything just to keep the 12V fridge ticking over.

I've been looking at the Honda EU22i and the Yamaha EF2200iS as potential backup options — both around the £1,000–£1,200 mark, which stings a bit. I'd only really be running it to top the battery up via a 20–30A DC-DC charger rather than running loads directly off it. Wondering if an hour or two every couple of days would actually be enough to make a meaningful dent, or whether I'd be constantly chasing my tail.

Has anyone gone down this route and actually found it practical for winter van life? Curious whether there are cheaper alternatives I'm missing — I've seen the Jackery-style power stations with pass-through charging but I'm not sure if that solves the actual problem or just adds another layer of complexity.

MattJones | 847 posts | ⚡ Solar Enthusiast

@CamperRachel Great shout for winter backup. I ran a Honda EU22i alongside my solar setup last winter and it worked a treat. The key thing nobody mentions is getting a decent "smart" charger or a DC-DC charger that plays nicely with your lithium — just plugging a cheap inverter generator into a basic charger can be really inefficient and hard on the battery.

Also worth considering runtime vs noise if you're on campsites — the Honda and Yamaha EF2200i are both genuinely quiet but pricey. The cheaper Chinese units like the Einhell or Hyundai ones are reasonable alternatives if budget's tight.

One practical tip: run it during daylight if possible so your MPPT can top off simultaneously. Made a noticeable difference to how quickly I could recover after a grim grey week in the Lake District! 😄

HappySpanner | 1,243 posts | 🔧 Tinkerer & Off-Grid Bodger

@CamperRachel Solid plan. One thing worth considering beyond just the generator itself — look at how you're connecting it. A proper transfer switch or even a basic changeover switch will make life much easier than fumbling with leads in the dark on a freezing January night.

Also worth noting that your inverter charger settings matter a lot. Make sure your charge current is set sensibly for a small genny — hammering it at full draw will make the thing work its little heart out and guzzle fuel. Dial it back to maybe 10-12A and it'll purr away efficiently.

Eco mode on most small inverter generators is your friend for this kind of steady charging work too. Quieter and kinder on fuel consumption.

What inverter/charger are you running currently?

BreezyCaptain | 412 posts | ⛵ Liveaboard & Van Dweller

@CamperRachel Definitely worth it for winter. One thing nobody's mentioned yet — keep an eye on runtime at partial load. Most small inverters are rated at full output, but you'll likely be running yours at 30-50% capacity most of the time, which actually improves fuel efficiency considerably. With your 100Ah lithium you can run the genny for an hour or two, top the battery right up, then shut it off rather than leaving it ticking over all day. Far more economical.

Also worth checking your battery's charge input limit — some 100Ah lithium packs will only accept 50A max, so there's no point pairing it with a massive charger. A modest 20-30A unit is often perfectly adequate.

What charger are you planning to use between the generator and the battery?

DucatoDream | 634 posts | 🚐 Narrowboat/Motorhome/Hut Obsessive

@CamperRachel Three winters ago I was exactly you — sat in my Ducato somewhere near Shrewsbury, laptop dying, cursing the grey skies like they'd personally offended me.

Picked up a Jackery-compatible inverter genny and wired it into my Victron MPPT via the shore power input. The real revelation was setting the Victron to only accept charge when battery dropped below 50% — so the genny isn't just chuntering away pointlessly.

For 200W solar and 100Ah, honestly even a 1kW inverter genny is overkill most of the time. You're topping up, not rebuilding from scratch.

One genuinely underrated tip: keep a fuel stabiliser in your kit. Nothing worse than a genny that's been sitting since October refusing to start in January when you actually need the thing.

LochSpirit | 2,891 posts | ☀️ Off-Grid Garden Office & Solar Nerd

@CamperRachel One angle I haven't seen mentioned yet — pay close attention to the generator's AC output quality before connecting it to a Victron MPPT or any smart charger. Cheap inverter generators sometimes produce a waveform that's technically "pure sine" but with enough harmonic distortion to confuse sensitive electronics.

For a 100Ah lithium specifically, you want the charger to see stable voltage and frequency. My Honda EU22i feeds into a Victron IP22 without complaint, but I tested three cheaper units before settling on it — two caused the charger to intermittently fault out.

Also worth sizing the generator below your charger's maximum input draw rather than at it. Running a generator at 80–90% load continuously shortens its service life considerably, particularly in cold Scottish winters like mine.

SolarTrevor | 187 posts | 🔋 Emergency Backup & Garden Office

Running a Honda EU22i alongside my garden office solar setup and it's been solid. For winter I basically treat the genny as a bulk charger rather than running it all day — fire it up for 90 mins in the morning, top the battery to 80%, then solar handles the float. Cuts fuel use massively.

With your 100Ah lithium you'd be in and out quick. Worth getting a proper smart charger rather than relying on the generator's built-in AC output directly — I use a Victron Blue Smart IP22 which plays nicely and gives you proper charge curves.

Also: fuel stabiliser if it's sitting unused for weeks between top-ups. Learnt that the hard way last February.