Ran out of power mid-January storm — here's what actually saved my cabin

Last month we had that brutal three-day storm that knocked out mains to half the valley. My cabin runs fully off-grid anyway (4× 200W Renogy panels, Victron MPPT, 200Ah Fogstar lithium), but three days of solid grey cloud with no wind is genuinely punishing. By day two I was sitting at 18% SoC watching the Cerbo GX like a hawk.

What actually pulled me through was my little "emergency tier" setup that I'd quietly built up over the summer — essentially a 240Wh Jackery 240 sitting permanently on a trickle charge from a single panel bypass, completely separate from the main bank. Fridge went off, I ran just the router, a 12V blanket, and phone charging from that little unit. Tiny loads only, but it bought me two extra days of warmth and comms.

The thing nobody talks about is sequencing — which loads you shed first and in what order. I've got a hand-written card stuck inside my consumer unit now with a numbered shutdown list. Sounds daft but at 2am when you're stressed you don't want to be making decisions.

Has anyone else built a proper "lifeboat" tier into their setup — completely isolated from the main system? Curious whether people use a second small battery bank, a generator, or something else entirely. Also wondering if there's any merit to keeping a small AGM just for emergencies even if you've gone full lithium elsewhere.

AndyJackson59 | 847 posts | Derbyshire

@InverterQueen Sounds like a rough few days but glad you came through it! Curious what your panel output was actually managing during those three days — I've found that even a moderate storm here in Derbyshire can drop my Renogy panels to genuinely pitiful figures, sometimes barely 10-15% of rated capacity.

The 200Ah Fogstar is a decent bank but honestly three days of grim UK winter weather is a real stress test. What was your daily consumption like? That's usually where people are surprised — often it's the heating elements or a kettle being flicked on that quietly murders the battery over 72 hours rather than any single big draw.

Did you end up running anything down entirely or did you manage to ration sensibly before it got critical?

WezMitchell94 | 312 posts | Cumbria

@InverterQueen Three days of storm in January with practically zero solar gain — that's a proper stress test. We had the same situation up here last winter and what saved us was having a rough "winter power budget" written on the inside of a cupboard door. Sounds daft but when you're tired and cold you stop doing the mental maths and start making bad decisions about what to run.

Curious what your baseline draw was sitting idle overnight? With 200Ah lithium you've got decent capacity but if the heating system's pulling anything significant it disappears fast. Did your Victron give you any useful retrospective data on where the power went? The VRM portal history is brilliant for post-mortems on exactly this kind of situation.

NeilAllen | 1,203 posts | North Yorkshire Moors

@InverterQueen Really curious what your actual loads were during those three days — that's often where people get caught out more than the generation side. January storms here can mean the panels are doing virtually nothing for 72+ hours, so it becomes purely a battery capacity question.

I had a similar situation two winters back and the thing that genuinely saved me was having audited my "essential only" loads beforehand — knew exactly what I could run and for how long. A small propane backup for heating rather than relying on electric made a massive difference to the energy budget too.

What did you end up doing for heat? That's usually the killer in these scenarios. Looking forward to reading the full story! 🏕️

DodgyNomad | 634 posts | Scottish Borders

@InverterQueen Cracking write-up, cheers for sharing the detail. One thing I'd add from bitter experience — 200Ah lithium sounds generous until you're running heating, lighting and keeping devices charged simultaneously for 72+ hours with virtually no recharge happening. The maths turns ugly fast.

What I've found essential up here is having a rough "storm budget" written down somewhere accessible — basically a worst-case daily Wh figure for absolute minimum loads only. When the weather closes in, you switch to that deliberately rather than discovering you've drifted over it.

@NeilAllen raises a fair point about actual loads too — would be really useful to know if you had any heating element drawing consistent current throughout. That's usually the silent killer in scenarios like this.

Chris1977 | 847 posts | Peak District

Really resonates with me, had a similar wake-up call two winters back. What it taught me was that battery capacity is almost irrelevant if your panels are buried under snow or producing next to nothing for days on end.

The thing that genuinely saved us was having a small Honda generator as a last resort, but more importantly, drastically cutting loads before we hit critical battery levels rather than after. By the time most people start panicking, they've already squandered the buffer they needed.

@NeilAllen raises a good point about loads — I'd be really interested to hear what you were actually running @InverterQueen. Heating is usually the killer. If you're relying on anything electric for warmth during a January storm, 200Ah disappears frightening quickly. Wood burner as primary heat changes everything.

T6Project | 89 posts | Array

What was your heating situation during those three days? That's what I'm trying to nail down for my own setup. I've got similar panel capacity but I'm paranoid about running any kind of resistive heating load when generation is basically zero.

Also curious whether your Victron MPPT was giving you any useful data through the VictronConnect app during the storm — I've been wondering whether it's worth setting low-voltage disconnect thresholds more conservatively for winter specifically, rather than keeping the same settings year-round.

Did you have any backup generation at all, or purely riding it out on the Fogstar bank? Three days of storm coverage with 800W of panels sounds genuinely grim — I'd have been rationing hard by day two.

TransitProject | 312 posts | Welsh Borders

Great thread, @InverterQueen. Heating is the killer variable @T6Project — worth separating your thermal load completely from your electrical budget if you can. I run a small wood burner as primary heat with a 12V fan (draws almost nothing) to circulate warm air. Keeps the electrical system purely for lighting, comms, and the odd charge. Even a basic propane backup heater buys you enormous breathing room during low-generation periods. The mistake most people make is assuming their battery bank covers everything simultaneously — compartmentalise your energy sources and you'll weather these events much more comfortably.

RhysGrant | 412 posts | Mid Wales

Really useful thread this. @T6Project heating is absolutely the killer variable — worth calculating your actual daily Wh consumption for whatever you're running before assuming your battery bank will cope. I've got a Webasto diesel heater which barely touches the electrics, draws maybe 10W once it's up and running. Completely changed my winter resilience. @InverterQueen I'd be curious what your load monitoring showed — did the Victron app give you decent retrospective data on where the amps actually went? That granular visibility is half the battle when you're trying to trim consumption under pressure.

BurnSophie | 247 posts | Array

Three days on the cut last February taught me exactly this. Heating was the thing that nearly broke me — I'd been running a diesel Webasto but the controller pulls a surprising amount of standby current overnight. Switched to a 12V Chinese diesel heater (Vevor, before anyone judges) and the draw dropped dramatically. The real lesson though: a small dedicated battery just for heating, isolated from the main bank. Even 50Ah of Fogstar kept my sleeping space liveable when everything else was rationed. @T6Project don't let heating and general loads fight over the same reserve — that's the separation that saved me.