The total amount of solar radiation energy received on a given surface area during a given time.
The solar power density incident on a surface of stated area and orientation, usually expressed as Watts per square meter or Btu per square foot per hour.
Insolation falls into Direct and Diffuse:
- Direct Insolation: Sunlight falling directly upon a collector. Opposite of diffuse insolation.
- Diffuse Insolation: Sunlight received indirectly as a result of scattering due to clouds, fog, haze, dust, or other obstructions in the atmosphere. Opposite of direct insolation.