Hukseflux SR20 Secondary Standard Pyranometer

For use where the highest measurement accuracy is required, secondary standard is the highest category in the ISO 9060 classification system

The SR20 measures the solar radiation received by a plane surface, in W/m2, from a 180 degree field of view angle. Released in February 2013 , it enables you to attain the highest measurement accuracy and excels in demanding applications.

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.



  • Measurand: hemispherical solar radiation
  • ISO classification: secondary standard pyranometer
  • Calibration uncertainty: < 1.2 % (k = 2)
  • Zero offset a: 5 W/m2 unventilated
  • Calibration traceability: to WRR
  • Spectral range: 300 to 2800 x 10-9 m (50 % transmission points)
  • Sensitivity (nominal): 15 x 10-6 V/(W/m2)
  • Rated operating temperature: -40 to +80 oC
  • Standard cable length: 5 m
  • Temperature response: <± 1 % (-10 to +40 °C); <± 0.4 % (-30 to +50 °C) with correction in dataprocessing
  • Temperature sensor: Pt100 or 10 kΩ thermistor
  • Heater: 1.5 W at 12 VDC


  • 4-20mA output version
  • Digital (ModBus) output version
  • custom cable lengths (standard 5m)


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