Has anyone run a wood burner and solar together in a small off-grid cabin through winter?

I've been setting up a little 20m² timber cabin on a plot in mid-Wales and I'm trying to work out the heating and power balance for the colder months. At the moment I've got a 400W solar array (two 200W panels) feeding into a 200Ah lithium battery via a Victron MPPT 75/15. In summer it's been brilliant — easily covering lights, a 12V compressor fridge, and laptop charging. But I'm nervous about January and February when we're getting maybe 2–3 hours of usable sun on a good day.

My plan is to run a small Hobbit stove (the 4kW one from Salamander) for heat, which should sort the warmth side of things fine. What I can't work out is whether to bother adding more panels or a second battery bank for winter, or just accept the solar will be limited and supplement with a small generator for the odd cloudy week. I've seen people mention thermoelectric generators that sit on top of wood burners — has anyone actually used one of those in a UK cabin context, or are they a bit gimmicky?

Would love to hear from anyone who's wintered in a similar setup, especially in Wales or the north where the sun really does disappear. What did you wish you'd done differently before your first proper winter?

Helen1994 | 312 posts | Powys

Yes, exactly this setup here in Powys! The key thing I'd add that people often overlook is thermal mass. My little burner heats the space brilliantly but it's cyclic - roaring hot then cooling down. I added some slate tiles around the hearth area which hold heat surprisingly well overnight.

On the solar side, be realistic - mid-Wales in January you might get 1-2 usable hours on a good day. I'd seriously consider a small wind turbine to complement the panels rather than throwing more solar at it. Our hills are rarely calm in winter!

Also @SophieClark worth getting a proper battery monitor so you're not guessing your state of charge. I wasted two winters doing that. The Victron BMV series is worth every penny for peace of mind. What battery chemistry are you running currently?

BoatMark | 847 posts | Afloat somewhere cold

Run almost identical on the boat — wood burner handles the heat while the Victron does the heavy lifting on power, and honestly they complement each other brilliantly because the warmer the cabin stays, the better your battery efficiency in those sub-zero Welsh nights (lithium really sulks when it's cold). One thing nobody mentions: a small 12V fan to circulate the burner heat doubles its effectiveness and costs almost nothing from your array. @Helen1994 is right about whatever she said before I got here, presumably. Also worth noting mid-Wales in January will have your 400W array producing roughly the output of a disappointed candle, so I'd seriously look at a small wind turbine to complement it.

MartinTaylor | 1,203 posts | Snowdonia

Great setup for mid-Wales, @SophieClark. One thing worth mentioning that nobody's touched on yet — thermal mass matters a lot alongside your wood burner. Even in a small 20m² cabin, a decent flagstone hearth or a couple of thick stone walls will hold heat overnight far better than timber alone, reducing how often you're feeding the stove.

On the solar side, I'd honestly say 400W will surprise you on clear winter days in Wales — you'll often get a decent 2-3 hour window of useful generation even in December. The real enemy is the grey week-long overcast stretches, so make sure your battery capacity can bridge those gaps comfortably rather than relying on regular charging.

What battery bank are you running currently? That'll probably be your limiting factor before the solar array itself becomes one.

Pylontech_Queen | 2,341 posts | Array

Static caravan here rather than a cabin, but the principle is identical. The thing nobody's mentioned yet is battery temperature — Pylontechs (and most lithium in general) won't charge properly once they drop below 5°C, which is very much a real-world Welsh winter problem.

My wood burner isn't just heating me, it's keeping my battery bank above that threshold. I've got my US2000s tucked in a small insulated compartment near the flue wall for exactly this reason.

Worth checking your BMS specs before assuming your batteries will just quietly top up on whatever weak December solar you get — @SophieClark, what chemistry are you running? If it's LiFePO4, low-temperature charge protection will kick in and your Victron controller should handle the cutoff gracefully, but you want the bank warm first.

DaiWalker61 | 412 posts | Brecon Beacons

I'm actually running almost this exact setup about 20 miles from you, @SophieClark — mid-Wales winters are a proper test! One thing I'd add that nobody's mentioned yet: a cheap thermostatic fan on top of the burner is brilliant for circulating warm air in a small space, and draws practically nothing from your batteries.

Also worth thinking about the wood moisture angle — seasoned hardwood makes a real difference to how often you're feeding the burner, which means less disruption overnight. Oak or ash if you can get it locally.

On the solar side, those winter days where cloud sits in the valley all week do happen. I'd say 400W is workable but keep an eye on your state of charge religiously from November onwards. What battery capacity are you running alongside it?

WattEd | 847 posts | Array

Something nobody's flagged yet: thermal mass interaction with your battery charging window. In a 20m² space, a small burner running evenings will push ambient temps up significantly, which actually helps your Victron MPPT regulation — lithium cells charge more efficiently above 10°C, and a cold shepherd's hut in January can see battery temps drop enough to throttle charge acceptance noticeably.

Worth fitting a battery temperature sensor if your MPPT supports one (most Victron units do). Let the controller compensate automatically rather than guessing.

Also on 400W in mid-Wales winters, expect realistic generation closer to 0.8–1.2 kWh on overcast days. Size your load expectations around that floor figure, not the panel rating. A Fogstar 200Ah LiFePO4 paired with a decent MPPT gives you reasonable headroom, but plan your heavy loads (kettle, hair dryer) for any brief bright spells.

WonkyWelder | 634 posts | Array

Running a similar cabin setup for emergency backup here. One thing worth adding — that wood burner will absolutely dry the air out, which sounds unrelated but your battery bank will thank you for keeping an eye on temps near it. I keep my Victron MPPT and Fogstar batteries away from direct heat on the opposite wall. Learnt that the hard way when my first setup got cooked. Also worth fitting a proper CO detector rated for low-level exposure, not just the cheap supermarket ones.