AMF02 mounting fixture

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.

An albedometer is an instrument that measures global and reflected solar radiation and the solar albedo, or solar reflectance. Albedometers are increasingly popular in bifacial PV module monitoring. An albedometer is composed of two pyranometers, the upfacing one measuring global solar radiation, the downfacing one measuring reflected solar.

You may use one AMF02 albedometer kit and two pyranometers of model SR20 to construct an albedometer of Spectrally Flat Class A, the highest accuracy class according to ISO 9060 (formerly known as ‘secondary standard’). AMF02 may also be combined with model SR11 pyranometers to construct a Spectrally Flat Class B albedometer.  The modular design facilitates maintenance and calibration. By taking the instrument apart you can use normal indoor calibration facilities for instrument calibration. SR11 and SR20 pyranometers are supplied with several outputs; analogue millivolts, 4-20 mA current loop and Modbus over RS-485 are the most commoly used.

AMF02 is easy to use. It allows you to combine two separate SR11 or SR20(-D2) pyranometers into one albedometer. Besides the two pyranometers and the AMF02 kit, all is needed is a set of tools. Required tools are hex key nr. 2,3,4 and 5. Mounting instructions are delivered with AMF02. AMF02 also includes a glare screen. A glare screen is a metal ring and is mounted on the downfacing sensor. At solar elevations of < 5 °, when the sun is just above the horizon, the glare sceen prevents that solar radiation is measured by the downfacing sensor. This is important becasause it would lead to unrealistic albedo measurements. Modern data quality assurance can also attain the data qualiy by calculating solar elevation and rejecting any data at solar elevations below a certain value for example < 10 °.