High efficiency screen-printed 156cm2 solar cells on thin epitaxially grown silicon material

This paper demonstrates an epitaxial silicon based technology from wafer to module that can greatly reduce Kerf loss and give high efficiency. Porous Si layer was formed on a reusable Si substrate to grow and transfer thin epi layers. 17.2% cell efficiency on thin, 156cm² large epitaxially grown Si (Epi-Si) wafers was achieved with tabs under glass/EVA. This is equivalent to ~18.0% uncapsulated cell tested in air, assuming 5% encapsulated loss. The built-in epi Back Surface Field (BSF) gave a Back Surface Recombination Velocity (BSRV) value of 500 cm/s. Bulk lifetime of 120us was achieved in ~3ohm-cm epi-wafers and no light induced degradation was observed in the cells. Further improvement of back passivation can lead to even higher efficiency.