Solar Irradiance Calculator Formula
Understand the math behind the solar irradiance calculator. Each variable explained with a worked example.
Formulas Used
Daily Irradiance
daily_kwh_m2 = peak_sun_hours * orientation_factorDaily Energy on Panel
daily_kwh_total = peak_sun_hours * orientation_factor * panel_area_m2Annual Energy on Panel
annual_kwh_total = peak_sun_hours * orientation_factor * panel_area_m2 * 365Variables
| Variable | Description | Default |
|---|---|---|
peak_sun_hours | Peak Sun Hours per Day(hours) | 5 |
panel_area_m2 | Panel Area(m²) | 20 |
orientation_factor | Orientation Factor (0-1) | 0.9 |
How It Works
Solar Irradiance and Energy Collection
Solar irradiance is the power of sunlight per unit area. Peak sun hours convert variable sunlight into an equivalent number of hours at 1,000 W/m².
Formula
Daily Energy (kWh/m²) = Peak Sun Hours x Orientation Factor
Total Daily Energy = Daily Energy x Panel Area
Peak sun hours vary by location: 3-4 in northern climates, 5-6 in temperate zones, and 6-8 in sunny regions.
Worked Example
A 20 m² array in a location with 5 peak sun hours and 90% orientation factor.
peak_sun_hours = 5panel_area_m2 = 20orientation_factor = 0.9
- 01Effective irradiance = 5 x 0.9 = 4.5 kWh/m²/day
- 02Daily energy = 4.5 x 20 = 90 kWh/day
- 03Annual energy = 90 x 365 = 32,850 kWh/year
Ready to run the numbers?
Open Solar Irradiance Calculator