Optics of Solar Concentrators. Part II: Models of Light Collection of 3D-CPCs under Direct and Collimated Beams

The optical properties of nonimaging solar concentrators irradiated in a direct mode by collimated beams are investigated in detail adopting original simulation methods. The adopted methods were not limited to investigate useful properties for the practical application of the concentrators, but were also used to know any aspect of them regarded as generic optical elements with specific transmission, reflection and absorption characteristics. We have investigated therefore, besides the transmitted flux to the solar cell receiver, also the flux back reflected from input aperture and the flux absorbed on the wall of the concentrator. The main results of the simulations were the transmission, reflection and absorption efficiencies, the average number of reflections of the transmitted or reflected rays, their angular divergence and the distribution of flux on the receiver or on the internal wall surface. The presented methods can be fruitfully applied to any other type of solar concentrator.