GC: n

CT: In Chapter 3, we defined the sun’s position angles relative to earth-center coordinates (ø δ and ω) and then to coordinates at an arbitrary location on the earth’s surface (α) and (A) and a functional relationship between these angles, i.e., Equations (3.13), (3.14) and (3.15). In the design of solar energy systems, it is most important to be able to predict the angle between the sun’s rays and a vector normal (perpendicular) to the aperture or surface of the collector. This angle is called the angle of incidence (θi). Knowing this angle is of critical importance to the solar designer, since the maximum amount of solar radiation energy that could reach a collector is reduced by the cosine of this angle.

S: http://www.powerfromthesun.net/Book/chapter04/chapter04.html (last access: 31 December 2014)

N: 1. In reference to solar energy systems: the angle a ray of sun makes with a line perpendicular to a surface; for example, a surface directly facing the sun has an angle of incidence of zero, and a surface parallel to the sun (such as a sunrise striking a horizontal rooftop) has an angle of incidence of 90°. Sunlight with an incident angle of 90° tends to be absorbed, while lower angles tend to be reflected.
2. angle of incidence (for direct radiation): The angle between the line joining the centre of the solar disc to a point on an irradiated surface and the normal to the irradiated surface.

S: 1. http://en.openei.org/wiki/Definition:Angle_of_incidence (last access: 31 December 2014). 2. GDT.

SYN:
S:

CR: solar energy, solar irradiance, solar radiation, solar thermal energy.