SRA11 albedometer

Analogue first class albedometer

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SRA11 first class albedometer

SRA11 first class albedometer is an instrument that measures global and reflected solar radiation and the solar albedo, or solar reflectance. It is composed of two SR11 first class pyranometers, one sun screen, one glare screen and one fixture with rod. Mounting hardware and tools are included. Each pyranometer has a thermopile sensor and offers output in millivolt; the upfacing one measuring global solar radiation, the downfacing one measuring reflected solar radiation. SRA11 complies with the latest ISO and WMO standards. The modular design facilitates maintenance and calibration.


Albedo, also called solar reflectance, is defined as the ratio of the reflected to the global radiation. The solar albedo depends on the directional distribution of incoming radiation and on surface properties at ground level. Albedos of typical surfaces range from about 4 % for fresh asphalt, and 15 % for green grass to 90 % for fresh snow. Using SRA11 albedometer is easy. The instrument is composed of two SR11 first class  pyranometers; the upfacing one measuring global solar radiation, the downfacing one measuring reflected solar radiation. The irradiance in W/m2 in each direction is calculated by dividing the pyranometer output, a small voltage, by the sensitivity. The sensitivity of both pyranometers is provided on the SRA11 product certificate. The working principle and specifications of the pyranometers can be found in the SR11 user manual. SRA11’s analogue output is in millivolt. SRA11 can be connected directly to commonly used datalogging systems.

Improved measurement accuracy

Calibration of SR11 pyranometer has been improved; our latest calibration method results in an uncertainty of the sensitivity of 1.8 %, compared to typical uncertainties of higher than 2.8 % for this pyranometer class.

SRA11 design

SRA11 consists of two identical pyranometers model SR11, one facing up, one facing down. The two sensors are delivered with one fixture with rod (15 x 10-3 m diameter) for mounting purposes. A glare screen is part of the delivery too. The user assembles these modular components into SRA11 albedometer. A mounting and fixation instruction is included.  The modular design of SRA11 facilitates maintenance and calibration. SRA11 can be ordered optionally with longer cable.

Suggested use

  • high-accuracy meteorological observations
  • building physics, roof reflectance studies
  • extreme climates (tropical / polar)


  • longer cables, in multiples of 5 m, cable lengths above 20 m in multiples of 10 m

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