Emissivity of solar cell cover glass calculated from infrared reflectance measurements

The thermal emissivity of solar cell cover glasses with differences in glass composition or manufacture and surface texture are evaluated using specular and specular + diffuse infrared reflectance at different angles of incidences. Non-textured and textured glasses all exhibit similar emissivity at all angles of incidence regardless of composition and patterning. Both diffuse and specular reflectance must be included for textured glass at any angle of incidence and may be needed for planar glass at a high angle of incidences to properly determine emissivity.