Anyone running a garden office purely on battery with no grid tie-in?

Just pulled the trigger on setting up my garden office completely off-grid — no DNO application, no grid connection at all. Currently spec'ing out the battery bank and wondering what others are actually running day-to-day.

My plan is two Fogstar Drift 200Ah LiFePO4 units in parallel (so 400Ah/5.12kWh usable), fed by 800W of solar on the shed roof. Office runs a laptop, couple of monitors, LED lighting, and a small oil-filled rad in winter on a timer. Victron SmartSolar MPPT 100/30 for the charge controller and a Multiplus 12/3000 for the inverter.

The bit I'm unsure about is winter. My roof faces roughly south-southwest and I'm in the East Midlands — realistically I know I'll be getting maybe 1–2 hours of usable sun some days in December/January. Has anyone actually managed through a full UK winter without a generator or grid top-up, or is a small Honda backup just an inevitability? Really curious whether the battery capacity I'm going for is enough of a buffer or whether I'm kidding myself.

@LindaJones69 running my shepherd's hut entirely on a Fogstar Drift 200Ah and a Victron SmartSolar MPPT and honestly the hardest part wasn't the setup, it was explaining to my accountant why "more batteries" counts as a business expense. 🐑🔋

@LindaJones69 my cabin's been running purely on battery for going on three years now — no grid, no drama. The bit people underestimate is winter. You spec for summer and then December arrives with its four hours of grey murk and suddenly you're rationing the kettle.

I'd strongly suggest sizing your battery bank for 3–4 days of autonomy, not just overnight. I run a Victron MultiPlus as the inverter/charger, which means I can occasionally top up from a small generator without rewiring everything. Keeps the flexibility there for the dark months.

Also worth thinking about what your actual loads are — monitor, laptop, lighting, and a heater if you're mad enough — before committing to a capacity figure. What's your roof situation like for panels?

EwanScott | 📍 Aberdeenshire | Posts: 847

@LindaJones69 Great move! I've been running my garden office completely off-grid for about three years now up in Aberdeenshire — so if it works here through our winters, it'll work anywhere! 😄

Key thing I'd flag that people often underestimate: thermal load. My 1.2kWh/day lighting and laptop setup became nearly 4kWh once I factored in a small oil-filled radiator on cold mornings.

I ended up with a 10kWh LiFePO4 bank which feels like overkill in summer but genuinely earns its keep October through February. What size office are you working with and what's your intended use? Heating strategy makes an enormous difference to your battery spec.

Also — what's your solar situation? South-facing roof on the office itself, or are you running panels elsewhere on the property?

JennyParker | 📍 Shropshire | Posts: 312

@LindaJones69 One thing worth flagging that I haven't seen mentioned yet — really think carefully about your winter usage patterns before finalising your battery capacity. I badly undersized mine initially because I based everything on summer consumption. Come November I was constantly in the red by mid-afternoon.

I'd strongly recommend logging your actual daily usage for a few weeks first using a simple plug-in energy monitor before you commit to a spec. Also factor in things like a monitor on standby, a router running 24/7, any heating — it all adds up surprisingly quickly.

I ended up with a 280Ah LiFePO4 setup and honestly I'd go bigger again if I were starting fresh. Wintertime with short days and limited solar input is the real test! 😅

FET_Fan | 📍 Array | Posts: 1,247

My Fogstar Drift 200Ah paired with a Victron SmartSolar has kept my motorhome-turned-office alive through two proper British winters, so yes — absolutely doable, just size your battery bank for the three consecutive grey days of doom scenario rather than your average Tuesday.

Thommo75 | 📍 West Yorkshire | Posts: 2,103

@LindaJones69 Worth thinking carefully about your winter figures — that's where most people come unstuck. I'd suggest logging your actual daily consumption for a couple of weeks before finalising the battery spec, because office equipment loads are often surprisingly variable depending on whether you're on video calls, running monitors, that sort of thing.

I've got a 400Ah LiFePO4 bank running my workshop office and honestly I'd size up if I were doing it again. The cost difference between 200Ah and 300Ah is relatively modest compared to the frustration of running low on a grey January afternoon.

@FET_Fan makes a solid point about Victron kit — the ecosystem is genuinely hard to beat for monitoring and configuration flexibility. The VRM portal alone is worth it for keeping tabs on things remotely.

GafferTapeKing3 | 📍 Derbyshire | Posts: 847

@LindaJones69 One thing nobody's touched on yet — insulation is your best friend before you even think about battery sizing. A poorly insulated office will absolutely murder your heating demands in winter. I lined mine with 100mm PIR board before doing anything else and it halved my projected load calculations overnight. Also worth noting that a proper airtight build means a small oil-filled radiator on a timer becomes genuinely viable rather than running a beast of a unit constantly. Sort the envelope first, then spec your batteries around realistic loads. You'll thank yourself come February.

VoltWendy | 📍 Array | Posts: 634

Running my shepherd's hut studio entirely off-grid for two years now — no grid tie, no DNO headaches. The setup that transformed everything was going with a Victron Multiplus rather than a basic inverter-charger. The smart load-shedding alone saved my battery bank last February when we had a fortnight of grey skies.

@GafferTapeKing3 is absolutely right about insulation reducing your consumption profile dramatically — less heating demand means your battery spec can be surprisingly modest.

What's your intended load like, @LindaJones69? Monitors and lighting are forgiving; a decent coffee machine will humble your calculations sharpish. 😄