SITE-INDEPENDENT ALGORITHM FOR OBTAINING THE DIRECT BEAM INSOLATION FROM A MULTIPYRANOMETER INSTRUMENT

The possibility of using the Perez irradiance model for reconstructing the beam and diffuse components of solar radiation from measurements with a fixed multipyranometer system is investigated. It is shown that an iterative algorithm can be derived that enables determination of the direct beam component to about +/-50 W/m2 without requiring any site-dependent adjustments. The standard error on the derived global irradiance on inclined surfaces of arbitrary orientation is at the +/-10 W/m2 level. It is concluded that the present degree of precision renders the multipyranometer method an attractive alternative to standard instrumentation for radiation surveys in remote regions. Possibilities for further improvements are discussed.