Deeply-grooved silicon concentrator solar cells for use with prismatic covers

Advanced-design 22-sun silicon concentrator solar cells that are compatible with and complementary to Entech prismatic covers are based on a deep, V-grooved silicon structure which reduces the sensitivity to minority carrier diffusion length. Additional benefits of this 3-D structure are reduced front-surface reflectance, increased light absorption and trapping, enhanced carrier collection, and reduced base series resistance. Large-area (38-cm² aperture) devices produced from 1.25-Ω-cm solar-grade silicon have open-circuit voltages as high as 683 mV and currents over 29 A. Initially, performance was limited by series resistance of the front contact due to the wide (20-mil) gridline finger spacing required to match the prismatic covers. However, cells fabricated with a finer contact grid have fill-factors of up to 0.828 at the design-point concentration