Off-Grid Cabin Solar Systems

First: Seasonal or Year-Round?

This is the most important question when designing a cabin solar system. A seasonal cabin (spring through fall) can get away with a smaller, simpler system because peak sun hours are higher and cold weather battery concerns are minimal. A year-round cabin needs to handle winter conditions: shorter days, lower sun angles (you may need tilted panels), and cold-weather battery management.

Typical Cabin Power Loads

Cabin System Configurations

Cabin-Specific Considerations

Generator Integration

A generator is an important backup for off-grid cabins — especially in winter. An inverter/charger (such as the Victron MultiPlus or Renogy Inverter Charger) automatically switches between battery, solar, and generator input. When the battery gets low and there's been no sun for days, the generator kicks in to top it up.

Generator tip: Run it at higher loads (60–80% capacity) for efficiency. A 2kW generator charging at full rate is more fuel-efficient than running it at 500W for four times as long.

Panel Tilt Angle for Winter

For year-round cabins, panel tilt should be set to your latitude + 15° for best winter output. In Montana (lat ~47°), that's 62° tilt — much steeper than typical summer-optimal 30–35°. Adjustable mount brackets (manual seasonal adjustment, two positions) are a cost-effective solution.

Cold-Climate Battery Management

LiFePO₄ batteries cannot be charged below 32°F (0°C). For a cabin, options are:

• Insulated battery enclosure — A well-insulated wooden or foam box with the batteries inside prevents rapid temperature swings. The batteries self-heat slightly from discharge.
• 12V heating pad — A thermostatically-controlled heating pad attached to the battery bottom activates only when needed.
• Self-heating batteries — RELiON InSight series and some newer Renogy models have built-in heaters that activate before charging at low temperatures.

Water System Considerations

A cabin water pump draws relatively little power (60W at ~15% duty cycle = ~216 Wh/day) but the pressure tank must be sized correctly. A standard 20-gallon pressure tank reduces pump cycling. If you have a deep well pump (230VAC, 1/2–1HP), you'll need a large inverter and possibly generator power for pumping.