Optical performance analysis of a HCPV solar concentrator yielding highly uniform cell irradiance

Here we analyze the optical performance of a novel solar concentrator design suitable for high-concentration photovoltaic (HCPV) modules. In the design, a pair of confocal parabolic reflectors and a Fresnel lens with matching focal length are employed to achieve high irradiance uniformity on the solar cell in an HCPV module. To evaluate the sunlight concentrating characteristics of this concentrator design, its peak concentration ratio (PCR) on the solar cell, overall optical efficiency, and acceptance angle are calculated numerically. Moreover, the dependence of these performance indices on the geometrical concentration ratio (GCR) and aspect ratio (AR) of the concentrator also is investigated, so as to identify the "optimal" concentrator geometry. It is thus demonstrated that, at a GCR of 800× for example, the concentrator design can limit the PCR below 1200× for all ARs greater than unity. Also, test data for a sample concentrator with 800× GCR and an optimized AR of 1.6 indicate that the enhanced cell irradiance uniformity enables an HCPV module to achieve an increased photovoltaic conversion efficiency of 28.6%.