CONCENTRATING SOLAR COLLECTORS.

Abstract

This chapter provides an introduction to concentrating solar collectors. The optical and thermal characteristics are described in relatively simple terms, and copious references to the more technical literature are given. A unified framework is used for analyzing the performance of all solar collector types; it involves optical efficiency, U-value, and heat transfer factor. Two measures of performance are of particular interest: the instantaneous efficiency under peak insolation (which is easy to measure), and the annual energy delivered by the collector (which is difficult to measure but is crucial for the economic evaluation). A simple but accurate graphical procedure is presented for obtaining the annual energy from the instantaneous efficiency curve. The chapter includes a discussion of practical aspects, covering choice of materials as well as problems of cleaning and tracking. Data for cost and performance of current collectors are provided.