Off-Grid Cabin Battery & Solar Sizing Guide
Design off-grid cabin power: daily kWh, battery bank size, solar array, and backup generator hybrid tips.
Mia Rodriguez · April 18, 2025·13 min read
Off-grid design starts with winter solstice sun hours, not summer peak production. Undersized winter arrays drain batteries for months.
Seasonal production tables
Model December production at 30–40% of July peaks for northern latitudes. Size battery banks to bridge multi-day storms.
| Month | Sun hrs | 3kW array output | Daily need | Surplus |
|---|---|---|---|---|
| July | 6.5 | 19.5 kWh | 8 kWh | +11.5 kWh |
| December | 2.1 | 6.3 kWh | 8 kWh | -1.7 kWh |
Generator hybridization
A small propane generator can top off batteries during extended storms, cheaper than tripling array size for rare weeks.
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