This project was conducted to determine the optimum silicon quality for cost-effective solar cells suitable for large-scale terrestrial utilization. The effects of selected impurities upon the solar cell performance were investigated by preparation and characterization of a matrix of silicon samples. Evaluation of the I-V curves to obtain the slope of the forward current of simple p-n junctions provided rapid material evaluation. Experimental techniques were demonstrated for achieving reliable data from diodes and solar cells. The primary electrical parameters measured were I-V characteristics. (auth)