Conflicting advice on battery bank sizing for a shepherd's hut — what actually worked for you?

Planning a small off-grid setup for a shepherd's hut I'm fitting out, and I keep getting wildly different answers depending on where I look. Some say 100Ah LiFePO4 is plenty for a modest setup, others say double it minimum. Getting a bit lost.

My estimated daily draw is around 30–40Ah — LED lighting, a 12V compressor fridge (Alpicool), phone/laptop charging, and occasionally a small fan. No inverter loads to speak of. I was looking at a Fogstar Drift 100Ah as the starting point, possibly two in parallel if needed.

Has anyone actually run a shepherd's hut through a full UK winter on something similar? Worried about the shorter days and how realistic it is to recover a smaller bank on a gloomy December day even with, say, 200W of panel.

Jake1977 | 847 posts

@DonnaMurray the conflicting advice usually comes down to people not knowing your actual loads. Before anyone can give you a sensible answer, work out what you're actually running and for how long — lighting, phone charging, a small 12v compressor fridge, laptop? They all add up differently.

For our shepherd's hut I ended up with 200Ah LiFePO4 and honestly I'd say that's the sweet spot for a comfortable but modest setup. The 100Ah crowd are often either just doing weekend use or wildly underestimating their consumption.

The rule of thumb I use: never plan to regularly discharge below 50%, so your usable capacity is effectively half whatever you buy. That changes the maths considerably.

What solar panel wattage are you pairing it with? That's equally important to the battery sizing conversation.

Will1961 | 412 posts

@DonnaMurray Jake's spot on about loads, but I'd add that seasonal use matters enormously too. Running a shepherd's hut through a British winter with short daylight hours is a completely different proposition to summer weekend use. I went with 200Ah LiFePO4 for my cabin setup and honestly I wish I'd gone bigger — not because 100Ah couldn't technically handle my loads, but because having that headroom means you're not constantly anxious about state of charge. Also worth factoring in your solar array size alongside the battery capacity, the two really need to be sized together rather than treating the battery in isolation.