Influence of grid finger and busbar structure on the performance of rear-line-contacted silicon concentrator cells

Silicon concentrator solar cells used in high concentrator systems (up to 500x) have a high potential to achieve cost reduction for solar generated electricity. Many different small-sized (4.5 mm x 4.5 mm) rear-line-contacted concentrator cells (RLCC), all integrated in one single wafer, were fabricated. These cells are designed for application in an one-axis tracking linear concentrator system with dielectric compound parabolic concentrators second stage. The best cell reaches a maximum efficiency of 24% at 63 suns and has a high performance under high concentration (23.2% at 265x). Experimental results show that the grid finger distance and especially the position of the bus bars influence strongly the performance of these cells. A two-dimensional model for these concentrator cells is presented and numerical simulations results are discussed.