Optics of Solar Concentrators. Part IV: Maps of Transmitted and Reflected Rays in 3D-CPCs

The transmission and reflection properties of nonimaging solar concentrators irradiated in direct mode by parallel light are investigated adopting original simulation methods. These methods were not limited to investigate useful properties for practical application of the concentrators, but were also used to study them as optical elements with specific transmission, absorption and reflection characteristics. In this work, we investigate the flux transmitted to the receiver and that back-reflected towards the entrance opening, by measuring the average number of reflections that the transmitted or reflected rays make on the internal wall of the concentrator. Results of this study are maps of the entrance opening, in which the different regions crossed by the transmitted or reflected rays are distinguishable and characterized by a different number of internal reflections. These maps are plotted for different values of the incidence angle of the parallel beam with respect to the optical axis of the concentrator. The presented simulation methods can be fruitfully applied to any other type of solar concentrator.