Solar Panel Requirement Calculator
Calculate how many solar panels you need based on daily energy usage.
Assumptions used in this calculation
- System efficiency: Assumes 80% overall system efficiency, accounting for inverter losses, wiring, and temperature derating.
About this calculator
Sizing a solar setup by simply dividing daily energy use by a panel's wattage rating badly understates the panels needed, because a panel only hits its rated wattage during hours of direct, full-intensity sun, and real systems lose some power to inverter and wiring inefficiency along the way. This calculator divides your daily energy consumption in watt-hours by the product of panel wattage, your location's peak sun hours (the equivalent hours of full-strength sunlight per day), and a system efficiency factor that accounts for those real-world losses, to give a realistic panel count. Enter daily energy use and peak sun hours for your location, and the calculator returns how many panels you'd actually need to install rather than a theoretical minimum that leaves you short on cloudy or shorter-daylight days. Because peak sun hours vary substantially by region and season, using a conservative, location-specific figure from a solar irradiance map gives a more dependable sizing result.
Worked example
10 kWh/day, 5 peak sun hours, 350W panels
Result: 8 panels needed
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