Anyone else using a small inverter-generator as winter backup for their static setup?

Picked up a Honda EU22i last autumn after two cloudy weeks nearly wiped out my Fogstar 200Ah LiFePO4. Solar just doesn't cut it November–February up here, even with a decent array.

Running it maybe once a week to top up when the bank drops below 20%. Takes about 2–3 hours at half throttle to get back to 80% through my Victron IP22 30A charger. Quiet enough not to annoy the neighbours and the fuel consumption is decent — roughly a litre an hour.

Wondering if anyone's done the maths on whether a bigger charger (Victron IP22 50A?) would actually save meaningful fuel and time, or whether the generator becomes the bottleneck anyway? Also curious if anyone's set up automatic start on something like this — seems like overkill for occasional use but I could see the appeal.

Victron_Master | 847 posts

@XJ_Solar completely understand the frustration — Scotland/North England winters are brutal for solar yield. The EU22i is a solid choice, very clean sine wave output.

One thing worth considering if you haven't already: pair it with a Victron MultiPlus rather than running the generator directly into a basic charger. The MultiPlus will automatically start pulling from the genny when your SOC drops to a set threshold, charge efficiently, and switch back to battery/solar seamlessly. Makes the whole backup process essentially hands-off.

Also worth running the generator at around 50-70% load for efficiency — chuck a decent charger profile on your LiFePO4 and you can top 200Ah up surprisingly quickly without burning much fuel.

What's your current charge controller setup? Might be able to suggest some tweaks to squeeze more out of those marginal winter days before the genny even needs to kick in.

Mark1970 | 312 posts

Same situation here — Midlands, so not as brutal as you lot further north, but December and January are still pretty grim for solar. I went with a Yamaha EF2200iS rather than the Honda, saved a fair bit and couldn't honestly tell the difference in real-world use.

One thing worth mentioning that I don't see discussed enough: get yourself a decent CO alarm and never assume "just outside the door" is safe enough. Had a near miss with fumes drifting back in through a vent last winter.

Also worth setting your Victron (assuming you're using one @XJ_Solar) to run an absorption cycle properly when the genny kicks in — lot of people just bulk charge and leave it, but you're not doing the battery any favours long-term.

HO_Marine | 164 posts

Motorhome rather than static, but same principle applies. I run a Jackery 500 as a buffer rather than going straight to mains charging — means the generator isn't cycling on and off constantly trying to maintain float.

One thing worth noting: if you're charging LiFePO4 via a generator, make sure your charger can handle the slightly "dirty" output some cheaper inverter-gens produce. The Honda EU22i is clean enough, but I've seen budget units cause issues with Victron smart chargers throwing faults.

@XJ_Solar what are you using between the generator and the battery? A proper DC-DC or just straight shore power into a B2B?

Winter solar in the UK is genuinely grim — I've got 400W on the roof and December yields are embarrassing compared to July. The generator stops the anxiety more than anything else.

RelayAdventure | 203 posts

Great thread. One thing nobody's mentioned yet — look into a proper smart charger profile if you're feeding the EU22i straight into your LiFePO4. The Honda's inverter output is clean enough, but pair it with something like a Sterling Pro Charge Ultra and you'll get a proper absorption/float cycle rather than just bulk dumping. Makes a real difference to how much you actually squeeze into the battery per runtime hour, which matters when you're trying to keep fuel costs down over a long winter stretch.

Also worth logging your actual generator hours each month — I was surprised how few hours it takes to top up if you're disciplined about only running it when the battery drops below 30%. Beats leaving it ticking over unnecessarily.

RhysGrant | 87 posts

Good timing on this thread — I went through exactly this last winter in mid-Wales. One thing worth mentioning that I haven't seen come up yet: generator placement and exhaust routing in cold, wet weather. I got caught out running mine too close to the outbuilding and had condensation issues internally. Now I've knocked together a simple vented shelter from a few pallets and some corrugated polycarbonate — keeps the rain off, lets the exhaust escape safely, and the EU22i runs noticeably more efficiently when it's not fighting the cold air directly. Also worth timing your generator runs to coincide with heavy loads like washing or cooking, rather than just bulk charging — kills two birds with one stone and your runtime hours stay low. @XJ_Solar how are you finding fuel consumption in the really cold snaps?