Anyone else running a wood burner alongside solar in a small cabin? How are you managing humidity?

We've got a little 20m² timber cabin in the Welsh borders that we use as a weekend retreat and occasional longer stays. Put in a 400W solar setup last year with a 200Ah lithium battery, which covers lighting, a 12V fridge, and charging devices no problem. The wood burner (a Hobbit stove, 4kW) is brilliant for heat but I'm starting to notice the humidity swinging all over the place — up when we're cooking or drying wet gear, then bone dry once the stove's been running a few hours.

I picked up a cheap SensorPush to track temp and humidity and I'm regularly seeing it drop to around 25% RH when the stove's going hard, then spike back up to 70%+ overnight when it cools down. That kind of cycling can't be great for the timber frame or the furniture long-term, and it's definitely noticeable on the skin and sinuses after a night's sleep.

I've been wondering whether a small 12V ultrasonic humidifier running off the solar would be worth adding, or whether I'm better off just putting a cast iron kettle or water pan on top of the stove. Also curious whether anyone's added any kind of HRV or trickle ventilation without losing all the heat — the cabin is pretty well sealed which is probably making things worse.

Has anyone cracked this in a similar-sized space, especially with a wood burner as the main heat source?

Reply by WrongFuse83:

@Ian1968 great little setup you've got there. One thing I'd flag from bitter experience — keep an eye on where you're placing any humidity sensors or electronics relative to the flue. I had a cheap hygrometer mounted too close to my stove and it was giving me completely wild readings because of the radiant heat skewing the sensor.

For the actual humidity management, a small 12V extraction fan on a timer running for 20 minutes after you've been cooking or drying wet gear makes a surprising difference without hammering your battery. Mine pulls maybe 2-3Ah for that cycle so barely registers.

Also worth checking your cabin's vapour barrier situation if it's timber framed — condensation inside the wall build-up is the silent killer in small heated spaces. Welsh borders winters are properly damp!

The humidity angle is one I've thought about a lot for my own backup setup. What I'd add is that the cycling is what gets you — wood burner cranks the RH down to 30%, you step out for the weekend, moisture creeps back in, repeat. That expansion and contraction is brutal on timber joints and, crucially, on any electrical connections in your battery enclosure.

Worth fitting a decent data-logging hygrometer (I use a cheap Govee unit) so you can see the actual swings rather than guessing. If your Victron BMV or MPPT is logging via VRM, you can sometimes correlate battery performance dips with the worst humidity events — useful diagnostic data.

A small passive vent with a humidity-activated damper near the battery bank specifically can help keep conditions steadier without losing heat constantly.

Reply by WezMitchell94:

@Ian1968 we ran almost exactly this combo in a 24m² cabin in the Cairngorms for two winters. The thing that made the biggest difference for us was a simple £30 hygrometer with a min/max log — you quickly learn when humidity spikes relative to your wood burner use and can adjust ventilation accordingly rather than just reacting. Also worth considering a small trickle vent on the opposing wall to the stove. Sounds counterintuitive in winter but even cracking it slightly when burning keeps the air exchanging without tanking your temperatures dramatically. Your solar setup sounds well sized for running a low-wattage dehumidifier overnight if needed too — something like a 22W compressor unit wouldn't touch your battery much. What species of wood are you burning? Unseasoned or softwood massively compounds the moisture problem in my experience.

Reply by Paddy_2634:

@Ian1968 nice setup for the Welsh borders — you'll definitely need that burner through winter! One thing nobody's mentioned yet is positioning your hygrometer away from the stove wall. I made the mistake of mounting mine near the flue and was getting wildly skewed readings. Aim for 45-55% RH ideally — below that and your timber joinery will start shrinking and gapping, above 60% consistently and you're asking for trouble with condensation behind any insulation panels.

Also worth thinking about ventilation timing — crack a window briefly just after you've got the burner going well rather than before, so you're not losing heat unnecessarily but you're still flushing any cooking or kettle steam out. Small cabin air volumes turn over surprisingly quickly.

What's your insulation situation like? That'll change the humidity picture considerably.