High collection uniformity three-dimensional V-trough concentrators

Abstract

Two-dimensional V-trough concentrators are widely used for photovoltaic applications since they can be implemented using low-cost fabrication method thanks to the flat surfaces. However, there is a trade-off between the effective concentration ratio and the concentrator ability to collect and concentrate the light uniformly from wide acceptance angle. The concentrated light uniformity is important to avoid the formation of hot spots on the solar cell that reduce the cell efficiency or causing damage. In this work, we present a novel design methodology and a set of optimal designs for three-dimensional V-trough concentrators maximizing the uniformity of collected light and acceptance angle at a higher concertation ratio shown to be C2 with respect to the two-dimensional case with a concentration ratio of C. A theoretical model is presented and compared to non-sequential ray tracing showing a good agreement. The non-uniformity is calculated as the ratio between the standard deviation and the mean of the value intensity on the cell. The acceptance angle is calculated based on the edge ray principle. The analysis shows that three-dimensional V-troughs suffer from slightly higher non uniformity than two-dimensional ones for the same acceptance angle. Example of the results show that the nonuniformity for C = 1.5 is increased from 0.29 to 0.39 and for C = 2.5 is increased from 0.18 to 0.22. The proposed designs can be used for wide acceptance angle concentration and tracking-free solar cells.