Circumsolar radiation telescope

A circumsolar telescope for determining the flux of energy from the sun and from the circumsolar region as a function of angle, wavelength, and atmospheric conditions is presented. The telescope system consists of a specially designed scanning telescope, an electronic control and recording system and some auxiliary equipment. The detector is a pyroelectric crystal, a type of thermal detector, thus the fundamental measurement is relatively wavelength insensitive. The telescope is designed to provide data for all weather conditions during which a concentrating solar energy system would be operating. Analyses show that for a clear blue sky, the amount of radiation coming directly from the sun, while for a sky with thin clouds or haze, the circumsolar radiation is some 25% of the direct solar radiation. Under such conditions a measure of the circumsolar radiation is necessary for an accurate prediction of the performance of a concentrating solar energy system.