Solar Energy Production Calculator
Calculate daily, monthly, and annual kilowatt-hour (kWh) solar electricity generation using system capacity, regional peak sun hours, and performance derate ratios.
Array Size & Sun Hours
Standard Solar Energy Generation Formula
Estimated Production (kWh) = System Capacity (kW) × Peak Sun Hours × Performance Ratio × Days- System Capacity (kW): DC nameplate rating of the solar panel array (e.g. 6.0 kW).
- Peak Sun Hours: Average daily hours when solar irradiance averages 1,000 W/m² (typically 4.0 to 6.5 hours across the US).
- Performance Ratio (PR): Real-world derating factor (typically 0.75 to 0.85) accounting for DC-to-AC inverter conversion losses, panel soiling, wire resistance, and high-temperature thermal losses.
Step-by-Step Worked Example
Calculation Steps:
How to Use This Calculator
Assumptions & Limitations
- Peak sun hours represent annual average solar insolation; generation is higher in summer and lower in winter.
- Performance ratio models standard roof angle tilt and orientation without severe tree shading.
Frequently Asked Questions
What is a 'Peak Sun Hour'?
A peak sun hour is not simply an hour when the sun is in the sky. It represents an hour during which solar radiation intensity averages 1,000 Watts per square meter (1 kW/m²), standard testing conditions for rating solar panels.
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