Off-Grid Solar Panel Sizing Calculator — Panels, Batteries & Charge Controller

Daily Appliance Loads

Appliance

Watts

Hrs/Day

Peak sun hours per day

Custom peak sun hours (if selected above)

Days of autonomy (cloudy days to survive)

System voltage

Battery type

Daily Energy Need

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Wh/day

Panel Wattage Needed

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watts total

200W Panels Needed

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panels

400W Panels Needed

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panels

Battery Bank

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Charge Controller

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amps (MPPT)

Oversize 20–25% — panels degrade 0.5–1% per year, and clouds/shading reduce real-world output.
LiFePO4 batteries last 10+ years and 3,000–6,000 cycles. Worth the upfront cost over lead acid.
MPPT charge controllers are 15–30% more efficient than PWM — always use MPPT for larger systems.
48V systems are more efficient than 12V for anything over 1,000W — lower current = thinner/cheaper wire.
Peak sun hours are your location's average daily equivalent full-sun hours — not total daylight hours.