The CM 21 Pyranometer is well suited for the measurement of incoming global solar radiation (305 to 2800 nm spectral range), as well as diffuse sky irradiance. Surface reflected solar radiation can also be measured.
The CM 21 pyranometer is designed for measuring the irradiance (radiant flux, Watt/m²) on a plane surface, which consists of direct solar radiation and diffuse radiation incident from the hemisphere above.

The CM 21 is a high precision pyranometer with strictly selected domes. Because of the high optical quality of these domes the directional error is reduced to less than 10 W/m².