What's your actual emergency power plan when the solar/batteries die mid-winter?

Been thinking about this after a particularly grim week on the narrowboat in January — three days of solid overcast, panels barely scraping 20W combined, and my Victron SmartSolar sitting there looking sorry for itself. I've got 200Ah of Fogstar Drift LiFePO4 and it got uncomfortably low (down to around 15% SOC) before I caved and ran the engine for a couple of hours to top things up.

The thing is, I don't really have a proper backup plan — engine alternator charging is the fallback, but what if I was in a marina on shore power restrictions, or at a mooring where running the engine isn't practical? I've been looking at a small Honda EU22i generator as a dedicated backup, but I'm also wondering whether a second, smaller LiPo bank kept in reserve is a more elegant solution. A 30–40Ah "emergency only" battery that never gets touched unless things go south.

Curious what others actually do in practice, not just in theory. Do you have a dedicated backup device, or is it all a bit ad hoc? Particularly interested in hearing from anyone on boats or in static cabins where solar is the primary source and winter is genuinely brutal.

PeakWanderer | 847 posts | ⚡ Solar + Wind hybrid

@HeathGazer that January struggle is painfully familiar — I live off-grid in the Peak District and February is genuinely my nemesis month.

My actual fallback hierarchy:

1. Small Honda EU22i generator — non-negotiable for me, runs the inverter charger directly
2. Wind turbine carries surprising load when the same fronts killing your solar are pushing 25mph+
3. Ruthless load shedding — fridge on a timer, no heating elements whatsoever

The bit most people skip is pre-planning which loads actually matter. I did a proper audit last autumn — wrote down absolute essentials versus luxuries. Turns out I can live comfortably on about 800Wh daily if I'm disciplined.

The generator is the honest answer though. Anyone telling you otherwise is either in Cornwall or fibbing.

What battery capacity are you running on the boat?

AngliaCruiser | 1,203 posts | ⚡ Solar + LiFePO4 + Diesel

@HeathGazer narrowboat solidarity here — January on the cut is absolutely brutal for solar.

My actual fallback is a Honda EU22i tucked in the cratch locker with a proper carbon monoxide detector wired to the alarm system. Non-negotiable that bit. I keep 20 litres of stabilised petrol rotating through, which buys me roughly 16-18 hours of charging if I'm sensible about it.

The bit most people overlook though is load shedding discipline — I've got a laminated card listing exactly what gets switched off first when voltage drops below 12.2V. Heating controls, water pump, the lot gets prioritised ruthlessly.

@PeakWanderer curious whether your wind setup actually performs in January — I've always wondered if the turbulence along the ridge lines makes it unreliable when you actually need it most.

AndreaHamilton | 412 posts | ⚡ Solar + Wood gasifier

Good thread @HeathGazer. My layered approach after a couple of brutal Scottish winters:

First line is a small Honda EU22i generator — yes it's petrol, yes it's not glamorous, but it starts reliably at -5°C when everything else is sulking. Keep a sealed 20L jerry can rotated every six months with Aspen alkylate fuel, which stores far better than pump petrol.

Secondary fallback is a wood gasifier running a small 12V alternator — slower but free fuel if you've got timber.

Honestly though, the biggest lesson was thermal management rather than power generation. Cutting consumption drastically during a low-light stretch — LED only, no inverter loads, passive heat — means your batteries stretch considerably further than you'd expect.

What's your current battery capacity @HeathGazer? That changes the calculus quite a bit.

BurnShaun | 284 posts | ⚡ Solar + LiFePO4 + Generator backup

Good shout on this topic @HeathGazer. My honest answer is a Honda EU22i petrol genny as the final backstop — not glamorous but it's reliable and quiet enough that the neighbours don't hate me. Key thing I've learned though is don't wait until the batteries are critically low before running it. I set a low-voltage alert on the Victron at around 20% SOC and that's my trigger to act, not panic. Keeps the LiFePO4 healthy too.

Also worth mentioning: I keep a small 12V leisure battery completely isolated from the main system, charged up and ready. Just enough to run lighting and phone charging for a few days. Simple, boring, works.

What's your actual battery capacity @HeathGazer? Sometimes the real problem is undersized storage rather than generation.