Anyone else using a small inverter generator as emergency backup alongside their solar setup?

Picked up a Honda EU22i a few months back as a winter backup for when we get those long grey weeks and the panels just can't keep up. Running a 400W solar array into a 200Ah LiFePO4 bank, which is usually plenty from around March through October, but January and February up here in Yorkshire can be brutal — three or four days of nothing and the battery's gasping.

The Honda's been brilliant so far, dead quiet compared to my old open-frame unit, and the eco-throttle means it's not guzzling fuel just to top up a half-flat battery. I'm running it through a Victron MultiPlus 12/3000, so the generator input gets conditioned before it hits the cells — takes about 90 minutes to bring the bank from 20% back up to 80% or so, burning maybe 0.6–0.7 litres of petrol. Not bad really.

Curious whether anyone else has found a sweet spot between generator runtime and solar capacity for winter resilience, or if anyone's gone down the dual-fuel route to cut running costs? Also wondering whether it's worth bumping my battery bank to 400Ah to reduce how often I'm firing the genny up — the maths seem to stack up but I'd love to hear real-world experience before I spend the money.

Got a battered old Kipor sat in the engine bay of my narrowboat for exactly this — solar's great until November decides it wants to be Scotland for six weeks straight, then you're just staring at a Victron display showing 11% SOC and questioning your life choices.

Great setup @DanHughes — the EU22i is a cracking choice for this. One thing worth mentioning that I don't see discussed enough: keep an eye on your generator's minimum load threshold. These inverter gennies can run rough or shut down if you're only drawing a trickle whilst the batteries are nearly full.

I run mine through a proper charge controller rather than directly into the inverter/charger, and I'll sometimes deliberately let the bank drop to around 40-50% before firing the generator up — means it runs for a solid productive session rather than faffing about at low load.

Also worth storing it with stabilised fuel if it's sitting unused for months. Learnt that the hard way last February when I needed it most! 😅

@FormerMechanic43 narrowboat life must make reliable backup absolutely essential — do you find the Kipor holds up reasonably well?

Has anyone actually wired their generator to charge the battery bank directly, rather than just running appliances off it? I've got a Victron MultiPlus in my static caravan setup and I think it can handle the input from a genny, but I'm not sure how fussy it gets about the EU22i's inverter-style output versus a conventional generator.

Also — does the EU22i's eco mode cause any issues when it's connected to a charger? Wondering if the load fluctuations mess with anything.

@RockyCaptain sounds like you were about to mention something useful before your post got cut off there, would be interested to hear the rest of it.

@SmartSolarNerd yes, and it's worth doing properly. Running mine through a Victron MultiPlus-II — the generator connects to the AC input, and the Multi handles the charging profile automatically via VE.Configure. You set a maximum shore current so you're not hammering the EU22i at full load, typically I run it at around 10A input limit which keeps the generator ticking over comfortably in eco-throttle mode.

Key thing people miss: LiFePO4 accepts charge so aggressively that a small inverter-generator can get overwhelmed if your charger isn't throttled correctly. The Multi's PowerAssist feature also means it can blend generator and battery output simultaneously, so you're not just bulk-charging — you can run loads at the same time without overloading the Honda.

Fogstar cells paired with a proper comms-enabled BMS feeding charge parameters back to the Victron makes the whole thing genuinely seamless.

Great thread! @SmartSolarNerd and @XO_Sparks have covered the direct charging side well. One thing I'd add from my own experience — if you're running the EU22i to charge via an inverter-charger, keep an eye on the charge current settings. These little Hondas are efficient but they don't like being loaded right up to their rated output continuously. I've found running mine at around 70-75% load keeps it happier for longer sessions and the fuel consumption stays sensible too. Also worth setting your inverter-charger to prioritise bulk charging quickly rather than a slow trickle — you want to get the job done and shut the genny off rather than running it for hours. Every hour it runs is noise, fuel cost, and runtime hours on the engine. Get in, charge up, get out!

Great points all round. One thing worth mentioning that hasn't come up yet — keep an eye on your generator's total harmonic distortion (THD) if you're running sensitive inverter chargers off it. The Honda EU22i is brilliant for this because its inverter output is genuinely clean (around 3% THD), which is why it plays nicely with kit like the Victron @XO_Sparks mentioned. Cheaper non-inverter generators can cause real headaches with modern chargers. Also worth doing a full test run every few weeks rather than waiting for a crisis — nothing worse than pulling it out in January and finding the carb's gummed up from sitting. A splash of fuel stabiliser in the tank goes a long way if it's sitting idle for months at a time.

@YM_Power raises a cracking point on THD that catches a lot of people out. Worth adding: the Honda EU22i is actually one of the better generators for sensitive electronics precisely because it's inverter-based — produces a much cleaner sine wave than a conventional genny. That said, I'd still recommend a transfer switch or proper integration rather than just plugging straight into your system willy-nilly. My shepherd's hut setup runs something similar and the difference between "generator as emergency measure" and "generator as properly integrated backup" is roughly the difference between surviving winter and enjoying it.

Really useful thread this. Just to add something I haven't seen mentioned yet — when you're running the EU22i to top up your LiFePO4, it's worth thinking about when you run it rather than just how. I tend to fire mine up in the morning if the forecast looks grim, so the battery goes into a dull day reasonably full rather than already depleted. Avoids that anxious cycle of watching the state of charge drop all afternoon. Small thing operationally, but it's made our winter routine a lot less stressful. Anyone else planning around weather forecasts like this?