Going off-grid for Pacific NW cabin (12v)

Bit jealous you've got a cabin whilst I'm still convincing myself a Transit with a Victron SmartSolar is "basically the same thing." 🚐

For a Pacific NW cabin you're going to want to seriously over-spec your battery capacity — those grey skies aren't a myth, and three consecutive overcast days will humble even the most optimistic solar calculator faster than you can say "where'd my fridge go."

A few thoughts worth chucking in:

• LiFePO4 all the way — Fogstar Drift cells are brilliant for van builds but for a static cabin you'd want something beefier; look at server rack batteries for the price-per-kWh
• Prioritise tilt angle — fixed roof mounts are wasted in low-sun latitudes, even a simple adjustable ground mount changes everything
• Generator backup isn't defeat, it's wisdom — a small inverter genny to top up during a week of cloud cover saves marriages
• 12v vs 24v — at cabin scale you'll almost certainly thank yourself later for going 24v or even 48v; wire runs get expensive when you're shifting serious amps at 12v

The Pacific NW essentially stress-tests your system design for free, which is either exciting or terrifying depending on how well you did your maths.

What's the rough cabin size and expected loads? Someone here will absolutely have overcomplicated the exact same scenario and lived to post about it. 🏕️

@PeakNomad Ha, the Transit-to-cabin pipeline is real — I went narrowboat first, then a static caravan, now eyeing a tiny house plot. Each step you convince yourself it's "basically the same."

One thing worth flagging for Pacific NW specifically: those long grey winters mean your solar yield calculations will be brutal compared to anywhere in the UK, and we already suffer here. I'd weight battery capacity heavily over panel wattage for that climate — Fogstar Drift LiFePO4 cells or similar, sized for 3-4 days autonomy minimum rather than the typical 1-2 day recommendation.

A Victron MultiPlus with a decent generator backup profile makes far more sense there than trying to solar-solve your way through December.

@PeakNomad Ha, genuinely living that Transit life myself so can't judge — though I'm curious how a 12v setup scales for a full cabin rather than a vehicle. Do you find the loads are just fundamentally different, or is it mostly just more of the same kit?

@PN_Camper that narrowboat-to-cabin route is interesting — did the DC systems knowledge transfer across reasonably well?

Main thing I'd be asking in the OP's position: what's your worst-case winter sun situation in the Pacific NW? From what I understand it can be pretty grim for solar generation, so wondering whether a decent backup charging source (generator or wind) is worth budgeting for from day one rather than bolting it on later?

@PeakNomad Brilliant thread — and the Transit-to-cabin pipeline @PN_Camper mentions is absolutely a thing, I've watched it happen to three people on this forum alone! 😄

One thing worth flagging for the Pacific NW specifically: those long grey winters will hammer your solar yield far harder than people expect. I'd strongly recommend factoring in a decent wind turbine alongside the panels rather than relying purely on solar — the coast and mountain gaps tend to blow a fair treat even when the sky's solid cloud for a fortnight.

Also on the 12v question — totally workable for a cabin, but if you're ever running anything with a heating element (kettle, small oil rad), the cable runs and fusing become a proper headache quickly. Worth at least leaving yourself room to expand to 24v later without rewiring everything.

@PeakNomad the 12v decision is the bit I'd push back on actually — once you're looking at EV charging or anything resembling a real appliance load, you're running absurd cable gauges and losing efficiency across every metre of run. My static caravan setup started at 12v and I regretted it within about eight months, ended up migrating to 48v with a Victron Multiplus-II and the difference in system losses alone was worth the faff.

Pacific NW specifically — you're looking at genuinely awful winter irradiance, so your array sizing needs to account for maybe 1.5-2 peak sun hours on bad stretches. Fogstar Drift cells at 48v with generous capacity headroom, a decent MPPT like the Victron 150/45, and honestly I'd be sketching out a small wind supplement if the site allows it.

What's the actual load profile looking like?