Incident Angle of Sunlight

When the Sun's rays are perpendicular to an absorbing surface, the irradiance incident on that surface has the highest possible power density. As the angle between the sun and the absorbing surface changes, the intensity of light on the surface is reduced. When the surface is parallel to the sun's rays (making the angle from perpendicular to the surface 90°) the intensity of light falls to zero because the light does not strike the surface.

Solar Energy

Solar energy is the radiant electromagnetic energy - or light - received from the Sun by the Earth. While the solar radiation received by the Earth's atmosphere is relatively constant, the amount of sunlight hitting the Earth's surface varies widely due to many factors including: