The effect of shading on the design of a field of solar collectors

Abstract

General expressions are derived for the shading and insolation of a field of solar thermal or photovoltaic collectors. The shading on a collector may be cast by its neighbour and/or by a fence, and is dependent on the spacing between collectors, and on collector height, row length, tilt angle and latitude location. The equations for the shadow height, length and area are given in dimensionless form and are therefore general relations. The derivations pertain to collectors arranged in rows in a horizontal plane, or raised in a step-like structure. The field may be oriented either towards the equator, or towards any azimuth. The equations for the collector insolation include the direct, diffuse and global insolation for the above collector fields. The variation of the shadow on the collector during the day is most important in solar system design, where the performance is highly affected by the shape of the shadow as found in photovoltaic systems. The results of this study may be used for the design and performance analysis of a field of solar collectors (thermal or photovoltaic).