Solar PV systems involve high-voltage DC and substantial fault currents. Improper installation can cause fire, injury, or death. Consult a licensed electrician and your local Authority Having Jurisdiction (AHJ) before any installation work, and verify every value against the current NEC edition and current product datasheets. Numbers and recommendations on this page are educational starting points, not a substitute for professional design and inspection.
Off-grid cabin
Solar setup for an off-grid cabin
A part-time off-grid cabin running on solar typically pulls 5–10 kWh/day, depending on whether you're heating and cooking with propane or running everything electric. Here's the build that handles a typical weekend/seasonal cabin with margin for the worst week of winter.
Typical cabin load profile
- Energy Star fridge — 80W avg, 24h → ~1,920 Wh/day
- Lighting (LED throughout) — 80W, 4h → 320 Wh
- Well pump (intermittent) — 750W × 0.5h/day → 375 Wh
- Laptop, phones, charging — 100W, 4h → 400 Wh
- Starlink / WiFi — 65W avg, 12h → 780 Wh
- TV, occasional → 100 Wh
- Microwave/induction occasional → 500 Wh
- Furnace fan (propane heat) — 150W, 4h → 600 Wh
Total: ~5 kWh/day for a propane-heat cabin. All-electric heat + cooking pushes past 10 kWh/day easily and changes the whole build.
Recommended build
Why these numbers
48V bank is the right call for any cabin above ~3 kW continuous load. Wire size goes down dramatically vs 12V (a 3 kW inverter pulls 250A at 12V but only 60A at 48V). Server-rack LFP modules (EG4 LL, SOK SK48V100) are the cleanest 48V option for DIY.
10 kWh battery covers two days of base load with zero solar input. For 3+ days of autonomy in cloudy weather, size up to 15+ kWh — but you'll pay roughly $400 per extra kWh installed in 2026.
2,000W of panels at a 4-hour-sun average produces ~6,400 Wh/day after derating — adequate margin over the 5 kWh load through three out of four seasons. In December at northern latitudes, you'll fall short — that's what the generator is for.
Hybrid inverter with transfer switch matters here. When the battery hits low SOC, the inverter automatically switches to generator power and runs the cabin while charging the battery. Without this, you're manually flipping switches in the cold and dark.
The generator math nobody mentions
Every off-grid cabin at northern latitudes needs a generator. Not because the solar system is wrong — but because two weeks of December overcast at 1.5 sun-hours/day will outrun any reasonable battery bank. A 3,500W inverter generator (Honda EU3000iS, Champion 3500) burns ~0.3 gal/hr at half load and can refill a 10 kWh bank in roughly 6 hours.
Plan to use the generator 5–15 hours per winter month in a typical northern build. Anyone telling you you'll never need one isn't being honest with you.
Plug your numbers into the builder →