The SRA20-D2 is composed of two SR20-D2 secondary standard pyranometers and one AMF02 albedometer mounting kit. AMF02 includes one glare screen, one mounting fixture with rod, mounting hardware and tools.

The pyranometers are individually tested for temperature and directional response and the SRA20-D2 is, therefore, the most accurate digital secondary standard albedometer available. The SRA20-D2 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. The instrument is composed of two SRA20-D2 digital secondary standard pyranometers; the upfacing one measuring global solar radiation, the downfacing one measuring reflected solar radiation. SRA20-D2 offers two types of outputs commonly used in the solar PV industry: digital via Modbus RTU over RS-485 and analogue 4-20 mA (current loop).