Design of dome-shaped non-imaging Fresnel lenses taking chromatic aberration into account

Concentration PV system is a technology for providing solar-based electricity at very high conversion efficiency of 40%. It needs solar concentration of 500 suns or more, for which the authors developed dome-shaped non-imaging Fresnel lenses with a certain acceptance half angle. As conventional design method uses only one wave length, the performance suffers from chromatic aberration. In this paper, a new design method is proposed. One of the points is that it uses two kinds of design wave length which covers a given range of solar spectrum for the concentration. The other is that new design points are located on the corners of prisms while the conventional point is at the center of prisms. Numerical examples with the concentration ratio of 500 were designed and optical efficiency was examined by ray tracing simulation. The results indicate that the lens based on the conventional way has dish-like shape and the lenses designed by the proposed method have relatively deep dome shape in contrast. The optical efficiency of the new design is better than that of the conventional one at the incident angle equal to the acceptance half angle. It was concluded that the proposed method could produce more effective solar concentrator with a certain tolerance of solar incident angle. 2011 Elsevier Ltd. All rights reserved.