The optics of the solar tower reflector

The concept of the reflective solar tower is based on inverting the path of the solar rays originating from a heliostat field to a solar receiver that can be placed on the ground. This system is based on the property of a ref lective quadric surface to reflect each ray oriented to one of its foci to its second focus. Two shapes of surfaces can be used: one is concave - the ellipsoid, and the other is convex - the hyperboloid (with two sheets), Thi s study analyzes the achievable optical performances of these types Of refl ectors and proves that the hyperboloidal surface is a superior reflector. T he optics of the hyperboloid are analyzed in detail. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.