Parametric optimization and performances analysis of four secondary optical elements for concentrator photovoltaic systems

Abstract

the study concerns a general, parametric and performances analysis of four secondary optical elements (SOE) to use for Concentrator Photovoltaic Systems (CPV) using the same primary optic element: the Fresnel lens (FL). It concerns the Compound Parabolic Concentrator (CPC), the Crossed Compound Parabolic Concentrator (CCPC), the Cone and Pyramid. The study starts from optical modeling and considers several classical materials, with various refractive indexes in order to get a clear idea about their influences on the efficiencies, the sizes and the geometrical needs of the SOEs. The performances of the whole concentrator systems are compared in term of achieved effective concentrations, acceptance angles, output light power distribution and tolerances in the placement of the secondary element regarding the FL. Based on the étendue law, the geometrical considerations reveal that the length and the input aperture size of the whole SOEs increase with the increase of the refractive index of the considered material. Results show that the pyramid-based concentrator gives the more uniform irradiance distribution and the high optical efficiency whatever the used material, and the largest tolerance angle never reported. At the end, to easiest the comparison of the four elements, a merit graph is developed and proposed