Davis Solar Radiation Sensor 
Solar Radiation Sensor
For use with Vantage Pro and Vantage Pro2. (Already included with Vantage Pro Plus and Vantage Pro2 Plus.)Measures solar radiation and is required (along with an anemometer and a temperature/humidity sensor) if you wish to monitor evapotranspiration.
Diffuser element and housing are carefully designed for accurate cosine response. Silicon photo diode provides good match to solar spectrum. Two-piece housing minimizes radiation heating, allows convection cooling of the sensor, and prevents the trapping of water or dust. Includes built-in level and 2' (0.6M) cable.
Compatible with both original Vantage Pro and Vantage Pro2.
You may also need a UV Sensor (#6490) and Sensor Mounting Shelf (#6673).
Quick Guide (pdf)
Owner's Manual (pdf)