Off-Grid Solar for a Cabin: Sizing, Cost and Installation
- A basic weekend cabin system costs $1,500–$3,000 DIY. Full-time cabin living needs $6,000–$15,000+.
- Size for winter — your worst sun month determines your system's capability year-round.
- Ground mounting is often better than roof mounting for cabins — easier access, optimal angle, no roof penetrations.
- A small generator as backup eliminates the need to oversize your battery bank for extended cloudy periods.
- Propane for cooking and water heating dramatically reduces your solar load and system cost.
Cabin solar by use case
| Cabin type | Solar array | Battery bank | DIY cost |
|---|---|---|---|
| Weekend getaway (basic) | 400W | 100Ah LiFePO4 | $1,200–$2,000 |
| Weekend getaway (comfortable) | 800W | 200Ah LiFePO4 | $2,500–$4,000 |
| Part-time (monthly stays) | 1,200W | 300Ah LiFePO4 | $4,000–$7,000 |
| Full-time (no AC/heat pump) | 2,000–3,000W | 400–600Ah LiFePO4 | $8,000–$15,000 |
| Full-time (with AC/heat pump) | 4,000–6,000W | 800Ah+ LiFePO4 | $18,000–$35,000 |
Typical cabin load calculation
Here's a worked example for a comfortable weekend cabin (2 bedrooms, fridge, lights, electronics, water pump — no electric heat or AC):
| Appliance | Watts | Hours/day | Wh/day |
|---|---|---|---|
| LED lighting (6 bulbs) | 60W | 5h | 300 |
| 12V compressor fridge | 50W | 12h (cycling) | 600 |
| Water pump | 60W | 0.5h | 30 |
| Laptop × 2 | 130W | 3h | 390 |
| Phone charging × 4 | 60W | 2h | 120 |
| TV (32" LED) | 40W | 3h | 120 |
| Router / starlink | 25W | 8h | 200 |
| Raw daily total | 1,760 Wh | ||
| With 25% losses | 2,200 Wh |
Three cabin build examples
Build A — Weekend cabin, Pacific Northwest ($2,800)
| Location | Oregon coast — 3.5 peak sun hours |
| Panels | 800W (2× 400W) |
| Controller | Victron SmartSolar 100/30 |
| Battery | 200Ah 12V LiFePO4 |
| Inverter | 1,000W pure sine wave |
| Mount | Ground mount, south-facing at 45° |
| Backup | 2kW generator for extended rain |
Build B — Full-time cabin, Texas ($9,500)
| Location | Texas Hill Country — 5.5 peak sun hours |
| Panels | 2,400W (6× 400W) |
| Controller | Victron SmartSolar 150/60 |
| Battery | 400Ah 24V LiFePO4 (9.6kWh) |
| Inverter | 3,000W pure sine wave inverter-charger |
| Mount | Roof mount, south-facing |
| Cooking/heating | Propane (not on solar) |
The propane strategy — reduce your solar load dramatically
Electric cooking and water heating are the biggest loads in a cabin system. Using propane for these functions dramatically reduces the solar system you need:
- Electric kettle: 1,200W × 5 min = 100Wh per use. Propane: free from solar's perspective.
- Electric water heater: 1,500W × 2h/day = 3,000Wh/day — would dominate any cabin system. Propane tankless heater: zero solar load.
- Electric range: 2,000W per burner. Propane range: zero solar load.
A cabin using propane for cooking and water heating might need 2,000–3,000Wh/day of solar. The same cabin with electric cooking and water heating might need 8,000–10,000Wh/day — 3–4× more solar and battery capacity.
Ground mount vs roof mount for cabins
| Ground mount | Roof mount | |
|---|---|---|
| Installation difficulty | Easier (no roof work) | Harder (heights, sealing) |
| Optimal angle | Easy to set | Fixed to roof pitch |
| Snow clearing | Easy access | Difficult |
| Shading risk | Higher (trees, terrain) | Lower |
| Cable run | Longer (underground) | Shorter |
| Recommended for cabins? | Usually yes | If roof pitch is good and no shading |
Winter considerations
Winter is the design constraint for any cabin system — especially in northern states:
- Snow on panels: Ground mounts can be tilted steeply (60–70°) to shed snow automatically. Roof mounts may need manual clearing after heavy snowfall.
- Reduced sun hours: December in Minnesota gets 2.5 peak sun hours vs 5.5 in summer. Size for December if you use the cabin year-round.
- Cold battery performance: LiFePO4 cannot be charged below 32°F without a self-heating model. Keep batteries in a space that stays above freezing, or buy self-heating batteries.
- Higher loads: Lighting runs longer, heating supplements needed. Winter loads can be 50–100% higher than summer.
Frequently asked questions
Can off-grid solar power a cabin well pump?
Yes, but well pumps are high-draw appliances (750–1,500W) that require a properly sized inverter. A submersible well pump also has a high startup surge — ensure your inverter's surge rating handles it. A pressure tank minimises pump run time, which helps. Many cabin owners use a 12V transfer pump to fill a gravity tank instead, significantly reducing the electrical load.
Do I need permits for a cabin solar installation?
Requirements vary significantly by county and state. Many rural counties have minimal requirements for off-grid systems, especially for seasonal or accessory structures. Check with your county building department. See our permits guide for state-by-state information.
What's the minimum system for a cabin that just needs lights and phone charging?
A 200W panel and 100Ah LiFePO4 battery ($600–$900 DIY) handles lights, phone charging and a laptop indefinitely in most locations. Add a 400W inverter for occasional AC devices. This is the most cost-effective entry point for cabin solar.