The 240-CSD3 Sunshine Duration Sensor provides the number of sunshine hours per day. The 240-CSD3 has no moving parts and uses three photo-diodes with specially designed diffusers to make an analog calculation of when it is sunny (direct solar irradiance greater than 120 W/m²). An output is switched high or low to indicate "sunny" or "not sunny" conditions. The calculated direct irradiance value is also available.
The 240-CSD3 operates from 12 Vdc power and has built-in heaters to dissipate rain, snow, and frost. These are normally switched externally but an optional internal thermostat control is available.
Sunshine duration sensors are widely used in weather networks to provide the number of sunshine hours per day for tourist information. In agriculture the 240-CSD3 monitors the amount of sunshine received by crops.