Development and Understanding of High-Efficiency Screen-Printed Concentrator Silicon Solar Cells

Concentrator cells have the potential to reduce the usage of semiconductor material while producing high efficiency and more power density in a cell. Silicon solar cells now provide a unique opportunity for low-cost concentrator systems that are suitable for low to medium (2-20X) concentration because cell technology and screen-printed contacts have improved considerably. In this paper, we report on the understanding and development of low-cost manufacturable screen-printed concentrator solar cells. Computer modeling was performed first to show that, under 10% metal coverage, it is possible for screen-printed cells to have series resistance that is low enough (<;0.29 Ω·cm²) to maintain high efficiency at low to medium concentrations. This was validated by design and fabrication of 40.56-cm² screen-printed cells using an industrial feasible process that achieved 18.8% peak efficiency at ~6 suns and 17.2% efficiency at 20 suns. Dicing a 9.9-cm² cell, which reduces the line resistance, raised the peak efficiency to 18.9% at 10 suns and 18.5% at 20 suns. Model calculations are performed to quantitatively establish the requirements for ~20% screen-printed 2-20X concentrator cells.