Higher efficiency for thin multi crystalline silicon solar cells by improving the rear surface passivation

For wafers thicker than 200 μm, the efficiency of industrial multicrystalline silicon solar cells is independent of wafer thickness. An important efficiency limitation of these thin solar cells is the poor rear surface passivation due to the short minority carrier diffusion length of the aluminium BSF. The most likely reason for the poor quality of the BSF is the poor crystallinity of the BSF due to fast cooling of the cells during metallisation firing. Possible solutions to overcome this limitation are presented.