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

I've been running a 2kW Hyundai HY2000Si petrol inverter genny as my fallback during the rubbish Scottish winters when the panels just aren't pulling their weight. Typically I'll only fire it up when my 200Ah LiFePO4 bank drops below 20%, which thankfully isn't too often — maybe four or five times between November and February. Fuel consumption is pretty reasonable, around 0.9 litres per hour at half load, so a full jerry can sees me right for a good while.

My main gripe is knowing when to run it efficiently. Right now I'm just plugging in a 20A AC-DC charger (a Victron Blue Smart 12/20) and letting it rip, but I'm wondering whether it makes more sense to run the genny harder and shorter or gentler and longer. I've read conflicting things about LiFePO4 charge rates and whether hammering it at a higher current causes any real long-term degradation compared to a slower top-up.

Has anyone done any proper testing or logging on this? I've got a Victron SmartShunt so I can pull data from the VictronConnect app — just not sure I'm interpreting it well enough to draw solid conclusions. Would love to know what setups others are running and whether anyone's found a sweet spot for charge current versus generator runtime.

@IslandDweller exactly the same situation on the boat — Scottish winters are brutal for solar yield, we're talking maybe 20-30% of summer output on a grey January day.

I run a Honda EU22i alongside a Victron MultiPlus, which means I can use the generator input to both charge the Fogstar Drift LiFePO4 bank and pass power through to AC loads simultaneously. Hugely efficient use of runtime.

One thing worth doing is setting your absorption voltage cutoff point carefully — hammering a lithium bank to 100% every generator run is unnecessary and adds cycle wear. I typically target 80-90% SOC via the generator, then let solar top up the rest when available.

Runtime ends up being surprisingly short — maybe 2-3 hours every few days rather than continuous running. Fuel consumption stays very manageable that way.

Great thread! I've got a similar setup — 2.2kW Honda EU22i running alongside my 3kW solar array in North Wales. The key thing I'd add that nobody's mentioned yet is fuel storage and rotation. I keep 20 litres of treated petrol (Aspen 4 or regular with PRI-G stabiliser) in proper jerry cans, rotating it every 3-4 months. Nothing worse than finally needing the genny during a January low-pressure system and finding the carb's gummed up from stale fuel sitting since October.

Also worth considering a small trickle charger setup so the genny's feeding directly into your battery bank rather than just running loads — much more efficient use of the runtime. @IslandDweller and @ForestBoater, do you both run yours through a proper transfer switch or just manual changeover? 🔋

Great thread! I've been running a 2kW Champion inverter genny alongside my solar for about two years now in the Peak District. One thing I'd add that nobody's mentioned yet — keep a close eye on your runtime hours and stick rigidly to the maintenance schedule. I learned the hard way that neglecting the oil changes on these small engines causes real headaches when you actually need the thing in January. Also worth considering a quality fuel stabiliser if it's sitting unused for weeks at a time — stale petrol in the carb is a nightmare. @ChrisCampbell90 what battery bank are you charging into with the Honda? I'm curious whether you're running it direct through a battery charger or via a proper inverter-charger setup, as that makes a significant difference to how efficiently you're topping up during those short winter run times.

Really useful thread this. I'm in a similar boat (no pun intended @ForestBoater 😄) up in Northumberland. One thing I'd add that nobody's mentioned yet — keep an eye on your runtime hours and do the oil changes religiously. I neglected mine over a particularly grim February and paid for it. Also worth thinking about fuel stabiliser if it's sat for weeks between uses, especially over summer. I use a small 2kW Kipor which has been solid for three years now. One tip: I run mine through a proper transfer switch rather than direct into the inverter, keeps everything cleaner and avoids any nasty back-feed issues. @PeteDixon89 what runtime are you typically getting per tank on the Champion?