Advanced metallization of rear surface passivated metal wrap through silicon solar cells

We present metal wrap through passivated emitter and rear cells (MWT-PERC) on p-type Czochralski silicon (Cz-Si) using advanced metallization approaches. Front surface metallization is performed either with a one-step approach (conventional thick film screen printing) or with a more advanced two-step approach, consisting of aerosol printing of a silver seed layer and subsequent silver electroplating. High short circuit current densities of up to 39.9 mA/cm2 indicate excellent light trapping and decreased front side shading due to the absence of busbars as well as high quality surface passivation. Both metallization technologies allow for conversion efficiencies of 18.7% for 125 x 125 mm2 sized Cz-Si MWT-PERC solar cells. Furthermore, we show the possibility of via metallization by the use of two-step seed and plate technology. Via resistances similar to those for screen printed via metallization are achieved. The seed and plate technology therefore forms a promising approach for via metallization of next generation MWT-PERC solar cells.