Solar Radiation - Understanding Renewable Energy Systems - page 70

Figure 2.21 Solar Position Diagram of Berlin with an Approximation of the
Surroundings

For further calculations, the degree of direct shading S dir is introduced. The
degree of shading describes the portion of the direct irradiance that is reduced
by shading:

S dir { 1

0 if ( γ S , α S ) is outside the object polygon

if ( γ S , α S ) is inside an opaque object polygon

1 - τ if ( γ S , α S ) is inside a semi-transparent object polygon

(2.37)

Figure 2.22 Shading Test for Two Different Positions of the Sun A and B
(Position A has 5 Intersections, Position B has 4)