Analysis of industrial c-Si solar cell's front metallization by advanced numerical simulation

The influence of the front metallization on the performance of industrially fabricated c-Si solar cells is quantified by means of a combination of optical, semiconductor, and circuit modeling. Special attention is given to the front metallization of conventionally processed emitters. First, we verify our model by reproducing the measured IV curves of industrially fabricated cells. Based on this, the potential changes in performance are predicted by variations in finger spacing, finger resistivity, busbar numbers, and contact resistivity. We also assess the benefits derived from the higher aspect ratios of the fingers: if the fingers are 120 (or 60 mu m) wide, increasing the finger height from 15 to 25 mu m increases their efficiency by 0.06% (or 0.7%) absolute if a conventional emitter is used. This implies that, if the fingers cannot be made as narrow as 60 mu m in industrial mass production, the economic gains from higher aspect ratios may be rather limited, because there is a trade-off between improved cell efficiency and the increasing cost of silver. Simulations show that, for the light-induced plating approach, the seed layer must be made as narrow as 50 mu m in order to achieve an efficiency gain of 1% absolute with a plating of 10 mu m silver. Copyright (c) 2011 John Wiley & Sons, Ltd.