Solar energy — Calibration of field pyrheliometers by comparison to a reference pyrheliometer

This International Standard is one of a series of International Standards specifying methods and instruments for the measurement of solar radiation. Pyrheliometers are used to measure direct solar irradiance. The data collected are used for — the determination of the efficiency of concentrating collectors, — the determination of the direct beam resource for concentrating solar energy devices as well as for determining their siting, sizing, etc., and — the accurate determination of hemispherical solar radiation as a sum of the measured direct solar and diffuse solar radiation. The calibration hierarchy of pyrheliometers specified in this International Standard follows the scheme developed by the World Meteorological Organization (WMO) [1], and the classification and specification used are prescribed in ISO 9060. During the elaboration of this International Standard, extensive reference was made to ASTM 816-81 [2].