Design of an off-axis XR photovoltaic concentrator with SMS method

We present a novel off-axis XR concentrator design that enables a high efficiency energy collection while avoiding the shadowing problem encountered in the designs of symmetry XR type concentrator. Combining with a 1 cm2 multi-junction solar cell, the off-axis XR concentrator is able to achieve high optical efficiency of the photovoltaic system. The concentrator design is performed based on the non-imaging optic principle, with one reflective mirror (X) and one refractive lens (R). Both surfaces of the reflective and refractive element are of freeform shapes and fitted as freeform expression in the design analysis. The concentrator has concentration ratio greater than 500× and acceptance angle greater than 2°. A square homogenizing irradiance distribution on the cell is achieved with the help of a suitable rob. The tolerance of the system is analyzed. The results show that the high concentration ratio and greater acceptance angle relax all optical and mechanical tolerances reduce the production and operation cost.