docs: def f_aoi(surface_tilt, surface_azimuth, solar_zenith, solar_azimuth):
      """
      Calculate angle of incidence
  
      :param surface_tilt:
      :param surface_azimuth:
      :param solar_zenith:
      :param solar_azimuth:
      :return: angle of incidence [deg]
      """
      return pvlib.irradiance.aoi(surface_tilt, surface_azimuth,
                                  solar_zenith, solar_azimuth)