Low-cost back contact silicon solar cells

Back-contacted solar cells offer multiple advantages in regard of reducing module assembling costs and avoiding grid shadowing losses. The investigate d emitter-wrap-through (EWT) device design has an electrical connection of the front emitter and the rear emitter grid in form of small holes drilled into the crystalline silicon wafer. The thus obtained cell structure is esp ecially suitable for low-cost base material with small minority carrier dif fusion lengths. Different industrially applicable solar cell manufacturing processes for EWT devices are described and compared. The latest experiment al results are presented and interpreted; especially the photo-current is f ound to be distinctly increased. The relation between open circuit voltage and rear side passivation is discussed based on two-dimensional (2-D) compu ter simulations.