SR20 is a pyranometer of the highest category in the ISO 9060 classification system: secondary standard. This solar radiation sensor is used where the highest measurement accuracy is required. It measures the solar radiation received by a plane surface, in W/m², from a 180 ° field of view angle.

Improved measurement accuracy

In order to improve overall measurement accuracy, Hukseflux effectively targeted two major sources of measurement uncertainty: calibration and “zero offset a”.

The initial calibration uncertainty is reduced to less than 1.2 %, an improvement of 15 % relative to competing models. The “zero offset a” specification of SR20 is 5 W/m² unventilated. Competing models state 12 W/m² unventilated and 7 W/m² ventilated.

Demanding applications

The temperature dependence of every individual instrument is tested and supplied as a second degree polynomial. This information can be used for further reduction of temperature dependence during post-processing. SR20’s low temperature dependence makes it an ideal candidate for use under very cold and very hot conditions. The incorporated heater reduces measurement errors caused by early-morning dew deposition.

SR20 pyranometer design

SR20 pyranometer uses a state of the art thermopile sensor with black coated surface, two domes and an anodized aluminum body. The connector, desiccant holder and sun screen fixation are ultra-robust and designed for industrial use. All parts are specified for use across SR20’s entire rated operating temperature range.