Limiting factors for the application of crystalline upgraded metallurgical grade silicon

Differently processed upgraded metallurgical grade silicon (UMG-Si) has been used to produce planar diffused solar cells. The results obtained from these cells were used to evaluate the limiting factors governing the conversion efficiency in UMG-Si-cells. The present state of practical cell processing was taken into account for the discussion of the potential of new technologies. For conventionally processed cells on UMG-Si having a planar junction, it appears that a conversion efficiency of about 13 percent under AM1.5 conditions (incident light intensity = 1 kWm^-2, T= 27°C) cannot be exceeded. Experimentally a conversion efficiency of 10.5 percent was obtained.