Abstract The rear side metallization of industrial PERC solar cells was investigated regarding the implication on the silver-aluminium-alloy formation, in particular the effect of the high resistivity alloy formation and the etching of surface passivation layer. By changing the dimensions of the printed silver-pads the size of the silver-aluminium-overlap region at the pad-aluminium interface were varied. The influence on fill factor and open circuit voltage are evaluated. For a three busbar cell design with six pads per busbar, the fill factor decreases up to 2.2%abs, if the overlap length between aluminium and silver pad is reduced from 12.5 mm to 1 mm, whereas the open circuit voltage increases by 2.5 mV. These results are additionally confirmed by a 3D simulation which validates the measurement results and shows perspectives for reducing the series resistance effect of the silver-aluminium overlap region up to 40% by increasing the busbar count from 3 to 5.
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