Large Area Screen Printed N-Type Silicon Solar Cells with Rear Aluminium Emitter: Efficiencies Exceeding 16%

We present low cost, screen printed industrial solar cells with a rear Al-emitter for n-type mono- and mc-Si large area thin wafers showing efficiencies of 16.4% and 14.4% respectively. The gap of 2% absolute between the cell efficiencies for mono- and mc-Si is not material related but is largely due to the non-textured surface of the mc-Si substrate. Applying a surface texture by acidic wet chemical etching could lead to efficiencies above 15% on the mc-Si material. The process is based on the standard industrial p-type firing through solar cell concept with slight modifications in individual processing steps similar to the Phostop cell presented by Ebara Solar. There is still need for further optimisation before industrialisation for instance in the fields of wafer bowing reduction and the implementation of AgAl pads for wafer interconnection. We propose two different ways of pad printing-one directly to the Al-emitter, the other on top of the Al rear contact