Search for Microstructural Defects as Nuclei for PID-Shunts in Silicon Solar Cells

Up to now, the formation process of stacking faults leading to PID-shunting of silicon solar cells is still unknown. In particular, the type of primordial defects that define the position of PID-shunts is of high interest. In this work it is experimentally proven that stacking faults evolve first under high voltage stress. At the same time, it is shown that stacking faults do not coincide with positions of threading dislocations. Furthermore, a correlation of regions with high PID-shunt densities is discovered at cells made from neighboring multicrystalline silicon wafers. This finding is discussed in terms of surface defect precursors that can act as nuclei for PID-shunts.