Anyone else running LiFePO4 in a garden office through winter — what capacity are you actually using?

Set up my garden office last spring with a 200Ah LiFePO4 (Fogstar Drift) and a couple of 200W panels. Worked a treat over summer, barely touched 50% DoD most days. Now we're deep into winter and I'm regularly hitting 80-85% DoD by mid-afternoon on overcast days. Yorkshire doesn't exactly get much sun in January.

Running a laptop, a couple of monitors, LED lighting and a small oil-filled radiator on a timer (1kW, maybe 3-4 hours a day). The radiator is clearly the killer. Thinking I either need more battery capacity or I ditch the electric heat entirely and go with a small wood burner or propane.

Curious what others are doing — especially if you're in the north or Scotland where the winter light is just as grim. Did you upsize your bank, or did you solve it on the load side instead? Tempted by another 200Ah to run in parallel but not sure it's worth it if the panels can't replenish it anyway.

@DalesWanderer — finish your sentence, man. Assuming you're about to say it's struggling.

Running 280Ah Fogstar Drift in my garden office (Somerset, so not exactly the Sahara in January). Two 400W panels on a 30° tilt and I'm regularly seeing 3-4 usable hours of generation on overcast days. The maths gets ugly fast.

Key lesson from last winter: your 200Ah summer headroom becomes your winter survival margin. I'm pulling about 160-180Ah on bad weeks before the sun bothers showing up again.

Practical fix that actually worked — I added a 240V mains trickle feed via a Victron Orion isolated charger, purely as backup. Purists will moan but I'm not freezing and losing billable hours to ideology.

What's your actual load in watts? Heating, monitors, laptop — that's where winter kills people's calculations.

@DalesWanderer same here — curious what loads you're actually running. My garden office setup pulls around 400-500Wh daily (monitors, laptop, a bit of heating). Winter's been rough with the panels barely producing 20% of rated output on grey days.

What's your solar input looking like? I've been seriously wondering whether 200Ah is even realistic as a standalone system through December/January without grid backup or a generator to top up.

Did you add any heating load, or is it purely work kit? That seems to be the real killer for capacity — even a small panel heater changes everything.

@DalesWanderer classic winter solar cliff-edge situation. The real killer isn't just reduced panel output — it's the combination of shorter charge windows and increased loads (heating, lighting).

Worth actually logging your daily Wh consumption properly if you haven't already. A Victron BMV-712 will give you accurate state-of-charge data accounting for the LiFePO4 discharge curve properly, rather than just guessing.

On a 200Ah pack at 24V that's ~5kWh usable (keeping above 10% SoC). If you're pulling 400-500Wh daily like @GrumpyWarden mentions, realistically in December you might only be getting 0.5-1.5 peak sun hours in Yorkshire/northern areas.

Do the maths — some days you simply won't break even. Parallel battery expansion or a small grid-tie backup is often the pragmatic answer rather than throwing more panels at it when roof/ground space is limited.

@DalesWanderer — yes, very much feeling this! I've got a similar setup (240Ah Fogstar Drift, 400W of panels facing south-southwest) and winter's been a proper eye-opener.

The thing that caught me off guard was how many consecutive grey days we get here in the UK — I'd planned around average irradiance figures but hadn't really accounted for four or five dull days back-to-back. I'm regularly hitting 80% DoD now whereas summer I rarely went below 70% SoC.

My honest advice: look at your worst-case consecutive low-generation days rather than monthly averages when sizing. I ended up adding a small hook-up cable to top up from the house mains on really grim weeks — not ideal for the off-grid purist in me, but keeps work uninterrupted. What loads are you actually running? That'd help figure out whether more capacity or a grid backup makes more sense for you.