When the highest data availability and measurement accuracy are key: Hukseflux SR25 pyranometer for measuring solar irradiance

When measuring solar irradiance professionally, high measurement accuracy and high data availability are key. Traditional high-end pyranometers, ventilated or not, do not offer both, due to dew and frost. Now Hukseflux has introduced SR25, the ISO 9060 secondary standard pyranometer with sapphire outer dome and internal heater. It offers the highest data availability, while maintaining its high measurement accuracy.

Hukseflux offers measurement solutions for the most challenging applications. Our main area of expertise is measurement of solar irradiance, for which we offer a complete range of sensors, systems and services. By developing and introducing SR25, Hukseflux takes solar radiation measurement to the next level.


SR25 is a secondary standard pyranometer, the highest class in the ISO 9060 classification, and is available with analogue and digital output. SR25 has a sapphire outer dome, glass inner dome and an internal heater. It employs a state-of-the-art thermopile sensor with black coated surface and an anodised aluminium body.

With its sapphire outer dome, SR25 pyranometer has negligible zero offsets. "Zero
offset a" is caused by a temperature difference between domes and detector. The high
thermal conductivity of SR25's sapphire outer dome ensures excellent thermal coupling
between body and domes. This results in a nighttime offset of < 2 W/m2, even when heated, unmatched by any pyranometer.

SR25 is heated in order to suppress dew and frost deposition, maintaining its high measurement accuracy. When heating SR25, the data availability and accuracy are higher than when ventilating traditional pyranometers. In addition, SR25 needs very low power; it only consumes 1.5 W compared to the usual 10 W for ventilation. The low thermal offsets make SR25 very suitable for measuring diffuse radiation. Patents on the SR25 working principle are pending.

SR25 is intended for all situations where ventilated pyranometers are employed, for diffuse measurements, PV system performance monitoring and environments with dew and frost.

More information and full specifications: http://www.hukseflux.com/product/sr25-pyranometer

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