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

I've had a Yamaha EF2000iS sitting in the shed for about three years now, mostly gathering dust because the solar and battery bank handles everything fine through spring and summer. But we had a proper grim January this year — weeks of overcast skies and barely 2–3 hours of usable light a day — and the 400Ah of LiFePO4 was draining faster than the panels could recover it. Ended up running the genny for a couple of hours each evening just to top things up.

What I'm trying to work out now is whether it makes more sense to run the generator straight into a battery charger (I've got a Victron IP22 30A), or whether I'd be better off picking up something like a Victron MultiPlus so it can do the generator integration properly with transfer switching and all that. The EF2000iS puts out about 1600W continuous, so a 1200W charger input feels achievable without flogging it. Has anyone done the sums on this and found a sweet spot for charge rate vs. generator run time?

Also curious whether anyone's had issues with the Yamaha inverter generators playing nicely with Victron kit — I've read mixed things about sine wave quality under varying loads and whether the MultiPlus can get fussy about it.

VM_Solar | 847 posts

@TracyRobinson The EF2000iS is a solid choice for exactly this role - that inverter output means you can safely run sensitive electronics without worrying about voltage spikes.

One thing worth doing if it's been sitting a while: run it on fresh fuel with a proper fuel stabiliser added, and give the carburettor a clean. Three years of occasional use can leave varnish deposits that'll let you down precisely when you need it most.

I've got a similar setup - Honda EU22i as my winter backstop - and I've found running it for 30 minutes every 6-8 weeks keeps everything happy and topped up. Also handy for bulk-charging the battery bank quickly during those grim January weeks when you're getting barely 2 hours of usable solar.

What's your battery bank capacity out of interest?

Mine lives in the motorhome's exterior locker doing precisely nothing from March to October, then suddenly becomes my best mate the moment a November cloud decides to park itself over Britain for a fortnight. 🏴󠁧󠁢󠁥󠁮󠁧󠁿☁️

DorsetCruiser | 312 posts

@TracyRobinson Same situation here - Honda EU22i tucked away until the dark months hit. One thing I'd add that nobody's mentioned: run yours under load for 20-30 minutes every couple of months even when you don't need it. I learned the hard way that sitting unused with old fuel in the carb leads to a very unhelpful machine precisely when you need it most. I now calendar a test run on the first Sunday of each month through winter. Also worth keeping a fresh can of ethanol-free fuel specifically for it - standard pump petrol goes off surprisingly quickly. The generator itself is brilliant once it's actually running!

MasterCamper | 1,247 posts

@TracyRobinson The EF2000iS pairs beautifully with a Victron MultiPlus if you've not already wired it that way — the PowerAssist feature means the inverter/charger only pulls what the genny can comfortably deliver, topping up from the battery bank simultaneously. Avoids that ugly overload situation when you've got something demanding running.

Worth noting: after prolonged storage, run it monthly for 20 minutes under load. Carburettor jets on these small Honda/Yamaha units gum up surprisingly fast on ethanol-blended fuel. Learned that the hard way last February when I needed it most and it wouldn't start cleanly.

My Fogstar 200Ah lithium setup handles everything April through September without touching it, but November–January in the motorhome it genuinely earns its keep during extended overcast spells.

CraftyGrafter | 203 posts

@TracyRobinson Snap! Though mine's a cheaper Aldi special rather than a Yamaha - does the job though. One thing I'd add that nobody's mentioned: keep a jerry can of treated fuel specifically for the generator. I learned the hard way that petrol left in the carb over summer turns to varnish and you're absolutely scrambling when you need it most. I use Briggs & Stratton fuel stabiliser now, added fresh every autumn. Also worth running it under load for 20 minutes every couple of months just to keep everything happy. Nothing worse than a January power crisis and a generator that won't fire. @DorsetCruiser does your Honda start reliably after sitting? I've heard they're brilliant for that but curious about real-world experience.

DebbiePowell76 | 89 posts

@TracyRobinson We're in almost exactly the same boat - Victron system with a Honda EU22i as the cavalry when January hits properly hard. One thing worth mentioning that nobody's touched on yet: do make sure you're running yours periodically through the year even if you don't need it. I learned the hard way that leaving petrol sitting in the carburettor over summer causes all sorts of grief - ended up with a gummed-up carb right when I needed it most during a February cold snap. Now I either run it dry after each use or add a fuel stabiliser. Also keep a spare spark plug taped to the generator itself - sounds daft but when you're cold and stressed at 9pm it saves rummaging through the workshop! @CraftyGrafter curious how the Aldi one handles surge loads?

CraftyWanderer | 412 posts

@TracyRobinson Interesting timing on this thread - I've just come through a rough November myself with barely a usable hour of sun some days. One thing I'd flag that nobody's mentioned yet: fuel degradation is a real gotcha with generators sat unused for months. I ruined a carburettor last winter through stale petrol. Now I either run it monthly for 20 minutes or use a fuel stabiliser like Sta-Bil. Also worth draining it completely before long storage. Sounds obvious but it cost me a 60-quid repair before I learnt my lesson!