Design Considerations of Small Solar Collector Systems Using Plane Heliostats

The primary advantage of the central receiver concept is the minimization of heat transmission in the form of enthalpy of a working fluid. This is replaced by efficient and low cost optical energy transmission. This characteristic renders collectors using heliostats to reflect solar radiation onto a stationary receiver attractive for small to medium scale, as well as large scale collection. This paper describes several years of design studies and simulations of central receiver systems scaled to be suitable for heating and cooling of commercial buildings or for some industrial process heat applications. The relatively small distances between the heliostats and receiver, vertical flat plate receiver geometry, and relatively low receiver result in optical simulation characteristics of such systems quite different to those of the large solar tower systems. The variation in radiation intensity over the surface of the receiver due to the relatively irregular shape of the insolated patch from a heliostat segment, and due to dispersion produced by off axis aberration in segmented heliostats, requires several unique features in the receiver design.