Pad printed front contacts for c-Si solar cells - a technological and economical evaluation

Transfer pad printing is a promising technique that allows overcoming restrictions of conventional screen printing regarding front side metallisation of c-Si solar cells. Within this work a pad printed front grid in an industrial process scenario is evaluated. Technological as well as economical aspects are addressed. Regarding technological evaluation, contact lines of 45 /spl mu/m printed on 10 /spl times/ 10 cm/sup 2/ wafers demonstrate the fine line printing ability of pad printing on large areas. The ability to print on uneven and fragile substrates like EFG material is proven. However, low paste transfer limits the line resistance and, thus, fill factor. Nevertheless, based on an extensive optimization of printing parameters including different pad types, values > 75% are achieved for double printing. Economical analysis reveals above 3% cost reduction per watt peak compared to state-of-the-art screen printing, taking into account the benefits of pad printing.