Optical design and demonstration of microtracking CPV module with bi-convex aspheric lens array.

A microtracking concentrator photovoltaics (CPV) module with a bi-convex aspheric lens array was designed, and its performance was numerically and experimentally verified. The lens shape was optimized considering the yearly incidence characteristics of direct solar radiation. The lens optimized at 127 × was found to converge 68.7% of the yearly cumulative direct solar radiation to solar cells and to be robust against changes in installation azimuth and tilt angles. The incidence-angle characteristics of a prototype lens agreed well with the design analysis. In an outdoor test using a prototype microtracking CPV module with an optimized lens and a triple-junction solar cell, the power generation was 1.32 times higher than that of the 17%-efficient Si cell and nearly 30% module conversion efficiency was achieved under clear sky conditions.