Anyone else running a small inverter generator alongside solar as a backup — worth it or more hassle than it's worth?

Been thinking about this a lot lately. I've got a 400W solar setup on my shed/workshop with a 100Ah lithium battery (Fogstar Drift), and it does the job most of the year. But we've had three or four really grim weeks this winter where the panels were producing next to nothing — talking 20–30W on a good day — and I ended up running an extension lead from the house just to keep things topped up. Felt like a bit of a defeat, honestly.

I've been looking at something like the Honda EU22i or the cheaper Hyundai HY2000Si as a petrol backup for those situations. The idea would be to run it for maybe an hour or two to dump charge into the battery via a decent charger (probably a Victron Blue Smart 30A), then switch it off. I'm not after constant runtime, just enough to bridge the gap when the sun disappears for days on end. Anyone done something similar? Did you go pure sine wave from the off, or did you try a cheaper modified sine unit first and regret it?

Also wondering about storage — keeping petrol fresh is a faff, and I've seen a few people mention ethanol-free fuel or stabiliser additives. Is that something most of you do routinely, or is it just forum overthinking?

@Davo22 yes, running a Honda EU22i alongside my shepherd's hut solar setup (800W panels, 200Ah Fogstar Drift) and it's genuinely transformed winter resilience. Key thing most people miss — don't just use it for direct loads, run it through a decent charger (I use a Victron IP22 30A) so you're bulk-charging the lithium properly rather than trickling in via the inverter's built-in charger.

Downsides worth knowing:

• Fuel storage becomes a consideration (HSFO regulations, degradation over time)
• EU22i is quiet but not silent — fine for daytime, awkward if neighbours are close
• Carb issues if left sitting with stale fuel

The real-world use case for me is three or four overcast January days in a row. Solar barely producing, battery down to 20% — generator does one 2-hour charge cycle and you're sorted for another day. Absolutely worth it for that scenario alone.

The integration question is worth thinking through carefully. Running an inverter generator purely as an ad-hoc top-up works, but you'll get more out of it by treating it as a proper AC charging source through a quality charger — a Victron Blue Smart or similar with configurable absorption/float curves will be far kinder to your Fogstar's cells than just plugging something directly in.

On my boat setup I use a Mase generator feeding a Victron Multiplus, which handles the transition logic automatically. Overkill for a shed workshop, obviously, but the principle holds — let proper charge management circuitry sit between the generator and battery rather than improvising it.

The real hidden cost with small petrol generators is fuel degradation during long storage. Ethanol-blended petrol goes stale fast. Either use treated fuel or run it dry between sessions, or you'll be rebuilding carburettors.