This function computes the solar angle of incidence on the plane-of-array, i.e. the angle between a line perpendicular (normal) to the module surface and the beam component of the sunlight. The tilt may be constant for fixed-tilt DC Fields, or variable for tracking DC Fields.

Inputs

Outputs

Algorithm

1.) Compute the incidence angle given an array of panel tilts β and aspects γ. The angle is defined
to be zero when the light ray is normal to the surface.

2.) Preserve the sign of the incidence angle to determine if the beam is behind the plane of the array.