HIGH EFFICIENCY SILICON SOLAR CELLS.

A polyvariable experiment was performed on PN solar cells to determine the optimum design for performance at solar intensities of about 350 mWsq cm. The region of maximum response was determined and indicated that a 13 line grid pattern combined with a 12 minute diffusion time would give the maximum performance for PN cells operated at solar intensities up to 350 mWsq cm. A bivariable experiment performed on PN polycrystalline cells has shown that polycrystalline cells can be optimized and designed for use in concentrated light systems. It was found that cell designs near the region of maximum response actually showed increased efficiencies at 316 mWsq cm equivalent solar intensities. The fabrication of cells having from 4 to 8 times the active area of the normal 1 x 2 cm cell indicates that large area cells can be made with short circuit current densities and open circuit voltages that compare quite closely with those obtained from 1 x 2 cm. Investigations have been made to determine methods of eliminating the time consuming and relatively expensive junction clean up etch with a more rapid, less costly process.