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. See surface_tilt. [°]

• surface_azimuth (numeric) – Panel azimuth. See surface_azimuth. [°]

• solar_zenith (numeric) – Solar zenith angle. See solar_zenith. [°]

• solar_azimuth (numeric) – Solar azimuth angle. See solar_azimuth. [°]

Returns:

projection (numeric) – Dot product of panel normal and solar angle. See aoi_projection.