pvlib.irradiance.aoi_projection

pvlib.irradiance.aoi_projection(surface_tilt, surface_azimuth, solar_zenith, solar_azimuth)

Calculates the dot product of the sun position unit vector and the surface normal unit vector; in other words, the cosine of the angle of incidence.

Usage note: When the sun is behind the surface the value returned is negative. For many uses negative values must be set to zero.

Input all angles in degrees.

Parameters:

surface_tilt : numeric

Panel tilt from horizontal.

surface_azimuth : numeric

Panel azimuth from north.

solar_zenith : numeric

Solar zenith angle.

solar_azimuth : numeric

Solar azimuth angle.

Returns:

projection : numeric

Dot product of panel normal and solar angle.