How much solar do you actually need?
Four steps on a napkin. No guessing, no sales pitch.
Four steps on a napkin. No guessing, no sales pitch.
Almost everyone buys off-grid power backwards — battery on sale, panels until the roof looks full, and they find out at 3am in February whether they guessed right.
Here's the math they skipped.
1. Daily watt-hours. Every appliance: watts × hours per day. A 12V compressor fridge pulling 50W but cycling about half the time is roughly 600Wh/day. Most modest rigs land between 800 and 2,000Wh.
2. Battery bank. Daily watt-hours × no-sun days, divided by system voltage. 1,500Wh × 2 days ÷ 12V ≈ 250Ah, plus headroom so you're not cycling to empty nightly.
3. Solar array. Your daily watt-hours divided by real sun-hours, derated ~25% for heat, wiring and angle. 1,500Wh ÷ (4 × 0.75) = 500W of panel.
4. Will it fit? Modern panels run about 18W per square foot, and real roofs lose space to vents and fans. That 500W array wants roughly 32 sq ft.
The Power Sizer turns your real appliance loads into a full spec — battery bank, solar array, controller, inverter and roof space — then matches it to gear that actually fits the number.
Open the Power SizerFree · no ads · no signup