Shepherd's hut solar setup — is 400W enough for year-round use?

Finally got the hut wired up properly last month. Running a Victron SmartSolar 100/30 MPPT with two 200W panels on the roof, feeding into a Fogstar Drift 12V 200Ah LiFePO4. Seems plenty through summer but I'm already nervous about winter.

Typical loads are fairly modest — a few LED lights, a 12V compressor fridge (about 40Ah/day), phone/laptop charging, and occasionally a small fan heater on the coldest nights (though I know that's asking a lot from 400W). The hut's in a valley so I lose direct sun early afternoon in November onwards.

Has anyone run a similar-sized system through a Welsh or Scottish winter? I'm wondering whether to add a third panel or just accept that I'll need a small generator as backup from October to March. The shading issue makes me think more panels won't fully solve the problem anyway — might be better off looking at a Renogy 40A DC-DC charger and running a leisure battery top-up from a genny rather than stacking more roof panels.

What's the realistic expectation here — am I being daft thinking 400W can cut it year-round in a shaded valley location, or is there something I'm missing with the setup?

@ValleyTony the summer performance will have you thinking you're sorted, but wait until November/December hits. I run a similar-ish setup on my static — 400W into a Victron MPPT and 200Ah LiFePO4 — and winter is genuinely brutal. Short days plus low sun angle means you're sometimes pulling maybe 20-30% of rated output.

Key question: what's your actual load? If you're just lighting, phone charging and a small 12V fridge you might scrape through. The moment you add any resistance heating or a laptop running all day, that 200Ah will be screaming by January.

Would seriously consider either a third panel if your roof allows it, or at minimum a small backup generator for the worst weeks. The Fogstar Drift is a solid battery though — decent investment.

Really solid foundation you've got there @ValleyTony — the Fogstar Drift is a cracking battery for the money. I'd echo what @CharlieStevens85 is hinting at regarding winter; the issue isn't just reduced sunlight hours but panel angle too. Worth checking whether you can tilt those panels steeper for the winter months — even going from 15° to 45° makes a noticeable difference in December when the sun barely clears the horizon up here.

Also, what's your main load? If you're running lighting and phone charging only, you'll likely manage fine. But if there's a small fridge or a laptop in the mix, I'd seriously consider a third panel or at least a small wind turbine as a backup input. The Victron handles multiple inputs beautifully. What's the hut being used for — weekend stays or longer off-grid periods?

Great setup @ValleyTony! One thing worth flagging that nobody's mentioned yet — panel orientation and tilt angle become really critical in winter at UK latitudes. If your panels are lying flat or at a shallow pitch, you could be losing a significant chunk of that already limited winter generation. Worth checking whether you can adjust them seasonally, or at least optimise for a steeper winter angle (around 55-60° works well for most of England and Wales).

Also, keep an eye on shading from low winter sun — even partial shading can hammer your output more than people expect. The Victron app will show you if something's off with your yield curves.

What's your actual load like day-to-day? Knowing what you're running would help gauge whether 200Ah is genuinely sufficient for your usage pattern through the dark months.

What's your actual load profile like @ValleyTony? That's the bit that determines whether 400W cuts it or not.

I've been running something similar on my boat and the numbers look great on paper until you factor in a couple of cloudy days back-to-back draining the bank faster than it recovers. With a 200Ah Fogstar you've got decent reserves, but what are you planning to run through winter — just lighting and phone charging, or are you looking at a 12V compressor fridge, laptop, heating controls?

The 100/30 controller is also worth checking against your panel configuration — are the two 200W panels wired in series or parallel? That affects your Voc input and whether you're actually getting the most out of the MPPT in low-light conditions.

Really good point from @GeoffHenderson80 — loads matter enormously. My static caravan setup taught me that the hard way. I had what looked like plenty of panel capacity on paper, but winter was brutal. December in the UK, you're looking at maybe 1-2 peak sun hours on a good day, and that's if your panels aren't sitting under a layer of frost.

The Fogstar 200Ah gives you a decent buffer, but I'd genuinely think about what happens across a run of grey days. Do you have any backup charging option — hookup point nearby, or even a small genny?

Also worth checking: is the SmartSolar configured for lithium profile? Sounds obvious but catches people out.

Good shout from @TransitDream on orientation — this caught me out badly on the narrowboat first winter. Even a well-sized system can surprise you when the sun barely clears the treeline from November through February.

The real killer on a shepherd's hut is often things people don't account for: phone charging, a small 12V pump, LED drivers that draw a sneaky parasitic load even when "off." On the boat I lost nearly 8Ah overnight to a faulty inverter sitting in standby.

Worth grabbing a Victron SmartShunt if you haven't already — watching actual consumption patterns over a fortnight told me more than any calculator ever did. That 200Ah Fogstar is a solid bank, but knowing exactly what's leaving it changes everything.

Winter in the UK is genuinely a different beast to summer. Plan for 2–3 days of near-zero generation and size your expectations accordingly.

Really solid setup @ValleyTony — the Fogstar Drift is a cracking battery for the money. One thing worth flagging that nobody's mentioned yet: December and January in the UK can give you genuinely dismal solar yields, sometimes only 1-2 peak sun hours on overcast days. With 400W that could mean pulling 80-100Wh from the panels on a bad day while your loads are higher. Worth running PVWatts or SolarEdge's calculator with your postcode and actual panel tilt to see your worst-case monthly figures. Might give you peace of mind — or flag whether a small wind turbine or generator backup is worth considering.

Winter's the real test tbh. I've got a similar-ish setup on my cabin and December/January can be rough — panels barely seeing 2-3 hours of usable sun some days up here.

The 200Ah Drift is a decent buffer but worth keeping an eye on your state of charge through the dark months rather than just assuming it'll cope.

One thing I'd add — any shading on that hut roof? Even partial shadow wrecked my numbers way more than I expected before I sorted it.