Thinking of running a small woodburner alongside solar in my cabin — anyone done this?

Finally getting serious about insulating and heating my 20-odd square metre cabin up in the Scottish Borders. I've got a 400W solar setup with a 100Ah lithium battery that handles lighting, a 12V fridge, and phone charging without much bother through summer. Come October though, it's a different story — the panels barely keep up and I'm sitting there in three jumpers wondering where it all went wrong.

I've been looking at a small 4kW woodburner, something like the Hobbit stove or one of the Charnwood Cub range. The cabin's well off-grid so I've got plenty of access to fallen timber, and I'd rather not go down the propane route if I can help it. My main concern is whether the flue installation through a timber-framed wall is going to be a nightmare, and whether a 4kW output is actually overkill for a space that small.

Has anyone run a small woodburner alongside their solar kit in a similar setup? Specifically wondering how you handled the flue — twin-wall through the roof versus a wall exit — and whether you needed building regs sign-off for a structure that isn't a permanent dwelling. Any horror stories or wins gratefully received.

@RustyCaptain solid combo for that square footage. One thing worth factoring in that often gets overlooked — a woodburner creates significant negative pressure in a small space if you're tightening up the insulation envelope properly. Make sure your air intake is ducted directly to the stove rather than relying on room air, otherwise you'll be fighting draft issues constantly.

On the solar/thermal integration side, I run a similar split in my van (obviously different context) — electrical for low-draw continuous loads, combustion for serious heat. The mistake people make is trying to electrify space heating when a decent 4–5kW multifuel stove renders that completely unnecessary.

For 20m² in the Borders, something like a Morso Squirrel or Charnwood Cub would be appropriately sized. Don't overspec the stove — oversized units run slumber too often and glaze the flue liner badly.

LochFinn | 847 posts | ⭐ Trusted Member

@RustyCaptain Cracking combination for the Borders — I run almost exactly this setup in a similar-sized place in Perthshire. One thing worth mentioning that people often overlook: a small woodburner with a back boiler can charge a thermal store, giving you domestic hot water essentially for free once you're burning anyway. Takes the pressure right off your solar during those grey November weeks when you're barely seeing 50W peak.

Also worth sizing your flue carefully for a 20m² space — you don't want a stove that's actually too powerful or you'll be roasting with the door cracked open all winter. A 4-5kW output is plenty for that footprint if your insulation is decent.

What's your wall construction like? That'll affect everything.

FZO_Marine | 312 posts | Verified Member

@RustyCaptain One thing I'd add that nobody's mentioned yet — think carefully about where you position the stove relative to your battery bank. Lithium cells really don't love sustained heat exposure, and in a 20m² space a decent woodburner can raise ambient temps considerably. Keep the battery in a ventilated spot away from direct radiant heat if you can manage it.

Also worth looking at a back boiler if you ever want domestic hot water sorted without touching your solar budget. Small investment, big quality-of-life improvement in the Borders winters. The DHW load alone would otherwise hammer your immersion and drain that 100Ah fairly sharpish on grey days.

Good luck with it — that part of Scotland is stunning but it'll test your setup in January, no question.

WattAMess | 203 posts

@RustyCaptain One thing worth mentioning — a small woodburner will actually help your solar setup indirectly during those grim Scottish winters. Rather than hammering your battery trying to take the edge off with electric heating, the burner handles the thermal load completely, leaving your 100Ah free for what lithium does best: lights, fridge, devices. Your solar generation will already be pretty miserable up there November through February, so keeping those two jobs firmly separate is smart thinking. Also worth looking at a back boiler if you ever want domestic hot water without a separate immersion — some of the compact 5kW stoves have them fitted or can be retro-fitted. Saves you running anything electric for that purpose.

TomButler | 156 posts

@RustyCaptain Good shout on the woodburner — done exactly this in my Northumberland cabin and it works brilliantly. One practical tip nobody's mentioned: get a stove with a built-in back boiler if you can stretch the budget. Even a small one lets you heat a thermal store passively, giving you hot water without touching your battery bank at all. For a 20m² space you honestly don't need anything rated above 4-5kW or you'll be roasting yourself out — I'd look at something around 3.5kW nominal output. Also worth checking your chimney positioning carefully relative to any roof-mounted solar panels; creosote deposits carried on the smoke can coat panels over time and knock your output back. Keep the flue exit well clear of the array if you can. Good luck with the build!

WildMechanic | 447 posts | Verified Member

@RustyCaptain Solid setup for a cabin that size. One thing I'd flag from personal experience — get your flue height and positioning sorted before you finalise the cabin layout. I bodged mine initially and ended up with downdraught issues every time the wind came off the hill at a certain angle. Cost me a whole weekend to reposition it properly.

Also worth looking at a back boiler unit if you ever want to expand — lets you heat a small thermal store and run a towel rail off the same fire. Overkill for some, but in the Borders winters you'll thank yourself. HETAS registration for the installer is non-negotiable too, even off-grid — don't let anyone tell you otherwise.

HamishLee | 312 posts

@RustyCaptain I'm running almost identical setup in a similar-sized cabin near Dumfries — 400W solar, small Hobbit stove. One thing nobody's mentioned yet: think carefully about where you position the flue relative to your roof and any overhanging trees. Up here in the south of Scotland the wind direction is unpredictable and a poorly positioned flue can downdraught badly in certain conditions. Also worth fitting a carbon monoxide detector regardless of how well-sealed you think the installation is. Small spaces make you vulnerable surprisingly quickly.