Hukseflux Thermal Sensors B.V

- Model SR22 - Secondary Standard Pyranometer



SR22 is a solar radiation sensor of the highest category in the ISO 9060 classification system: secondary standard. On top of the features and benefits of the successful SR20 pyranometer, SR22 has domes made of high-quality quartz, resulting in an extended spectral range. Covering the full solar spectrum, SR22’s extended spectral range potentially offers lower measurement- and calibration uncertainties compared to pyranometers with glass domes. SR22 is typically used in high-accuracy climatological networks.

SR22 measures the solar radiation received by a plane surface, in W/m2, from a 180o field of view angle. This ISO 9060 secondary standard pyranometer enables users to attain the highest measurement accuracy and offers the widest spectral range commercially available. SR22 has an onboard temperature sensor. When using SR22, additional ventilation is recommended. SR22 is typically combined with ventilation unit VU01.

Extended spectral range

On top of the features and benefits of SR20 pyranometer, SR22 has an inner and outer dome made of high-quality quartz. This results in SR22’s spectral range of 190 to 4000 x 10-9 m. SR22 covers the full solar spectrum, including the part between 3000 to 4000 x 10-9 m, which is not measured by pyranometers with glass domes.

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 less than 1.7 %. The “zero offset a” specification of SR22 is 5 W/m2 unventilated. Ventilated (with VU01) it is just 2.5 W/m2.

SR22’s low temperature dependence makes it an ideal candidate for use under very cold and very hot conditions. 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.

SR22 pyranometer design

SR22 pyranometer uses a state of the art thermopile sensor with black coated surface, two quartz domes of the highest quality and an anodised aluminium body. The connector, desiccant holder and sun screen fixation are very robust and designed for industrial use. All parts are specified for use across SR22’s entire rated operating temperature range.

Suggested use

  • scientific climatological observations
  • reference instrument for comparison
  • extreme climates (tropical / polar)


  • longer cable, in multiples of 5 metres
  • ventilated with VU01 ventilation unit

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