Interactive Demo

Solar Irradiance Simulator

Calculate Global, Direct, and Diffuse solar irradiance (GHI, DNI, DHI) for any location. Based on the Kasten-Young and Cooper models for atmospheric corrections.

Select a City

Quick presets for major global cities

Location Parameters

°
°
m
UTC

Panel Configuration

°
°

Solar Information

🌅
Sunrise
--:--
🌇
Sunset
--:--
📅
Day of Year
--
📐
Declination
--°
🔆
Max Elevation (Solar Noon)
--°

Simulation Results

GHI Total (Global)
-- kWh/m²
☀️
DNI Total (Direct)
-- kWh/m²
🌤️
DHI Total (Diffuse)
-- kWh/m²
📐
GTI Total (Tilted)
-- kWh/m²

Daily Irradiance Profile

GHI DNI DHI GTI

Hourly Data

Hour Elevation GHI (W/m²) DNI (W/m²) DHI (W/m²) GTI (W/m²) Status
Run simulation to see data

How It Works

1

Solar Position

Calculate solar declination using Cooper's formula and true solar time from longitude and timezone.

2

Zenith Angle

Compute the solar zenith angle based on latitude, declination, and hour angle throughout the day.

3

Air Mass

Use Kasten-Young (1989) formula for accurate air mass calculation at high zenith angles.

4

Transmissivity

Apply Beer-Lambert law with altitude and pressure corrections for atmospheric attenuation.

5

Irradiance

Calculate DNI, DHI, and GHI using the decomposition: GHI = DHI + DNI × cos(θz).

Key Formulas

Global Horizontal Irradiance
GHI = DHI + DNI × cos(θz)
Direct Normal Irradiance
DNI = S₀ × τm × f(altitude)
Solar Declination (Cooper)
δ = 23.45° × sin(360/365 × (284 + n))
Air Mass (Kasten-Young)
AM = 1 / [cos(θz) + 0.50572(96.08 - θz)-1.6364]