Anyone else running a small cabin purely on LiFePO4 + solar through a British winter?

Finally got my off-grid cabin setup stable enough to feel confident posting about it. Running a 400W Renogy panel array feeding into a Victron SmartSolar MPPT 100/30, with a 200Ah Fogstar Drift LiFePO4 battery. Inverter is a Victron Phoenix 12/1200. Tiny footprint but it covers lighting, a small laptop, phone charging and the odd power tool.

Winter has been the real test. Shortest days I was seeing maybe 0.8–1.2kWh generation on a decent day, which barely keeps up with my evening loads. I've had to get pretty disciplined about what I run and when — basically nothing heavy after 3pm unless I've had a genuinely sunny afternoon.

What I'm struggling with is heating. Currently using a small wood burner for the bulk of it, but I'm tempted to add a diesel heater (thinking a Vevor or an Espar unit) for overnight use without stoking a fire at 2am. The power draw on those is manageable once running — but the startup spike is what concerns me with a 1200W inverter on a 12V system.

Has anyone run a Chinese diesel heater through a similar Victron setup over winter? Curious whether the startup surge caused any issues, or whether I'm overthinking it.

LesHarris | 847 posts

@CrafterSolar Nice one, congrats on getting it stable! The Fogstar Drift is a solid choice - good to see more people moving away from AGM for cabin setups.

One thing worth mentioning that catches people out through winter: keep an eye on your panel angle. I dropped mine to about 60° from October onwards and it made a noticeable difference to those low winter sun harvests. With only 400W you'll want to squeeze every amp out of those short grey days.

What's your main load situation? Lighting and a few USB devices is manageable, but if you're running any kind of heating element even occasionally, that 200Ah will feel quite tight by February. Curious what consumption you're averaging daily. 👍

Cabin on LiFePO4 through a British winter is basically just paying Fogstar to store clouds for you.

SmartSolarGuy | 312 posts

@NBW_VanLife 😂 "storing clouds" — that's going on a t-shirt.

Running my cabin through last winter on a similar setup taught me one brutal lesson: it's not your battery capacity that saves you, it's your baseline load discipline. I stripped everything back to what I actually needed after a four-day January grey spell nearly wiped me out.

The Victron SmartSolarGuy app became my morning ritual — coffee in hand, checking yesterday's yield like I was reading the weather forecast. Because essentially, I was.

Key thing I'd add for @CrafterSolar: get your low-voltage disconnect dialled in properly on the Victron. LiFePO4 doesn't warn you the way AGM does — it just... stops. Found that out the hard way in February when my router died mid-Teams call. Cabin life, eh.

PW_Sparks | 1,203 posts

@CrafterSolar Great setup! One thing worth keeping an eye on through winter is your MPPT's low-temperature charging behaviour with the Fogstar. LiFePO4 really doesn't like being charged below 0°C, and a frosty Scottish morning can catch you out if the BMS cuts in unexpectedly. The Drift's built-in BMS should protect it, but worth double-checking your Victron charge profile matches Fogstar's recommendations.

Also — 400W feels tight for January/February. Even in the South you're looking at maybe 1-2 peak sun hours on a grim day. What's your rough daily consumption? Might be worth sharing your load profile so folk here can give more specific advice on whether you've got enough headroom. 👍

GrumpyWarden | 47 posts

Running something similar on my garden office — 200W Renogy panels with a Fogstar battery. Genuinely curious: how are you handling the low-temperature charging cutoff on the Drift? Mine kicks in around 5°C and on a frosty November morning that's basically every day before 10am.

Have you got any heating on the battery itself, or are you just accepting the lost morning charging window? I've been wondering whether a small self-regulating heat mat wired to a temperature relay is worth the faff, but not sure if the energy cost eats into any gains.

Also — what's your actual usable capacity looking like on a typical overcast December day? I'm trying to work out whether 200Ah is realistically enough or if I should be looking at expanding before next winter.