significant improvements in open-circuit voltage and conversion efficiency, even on relatively high bulk resistivity silicon, were achieved by using a screen-printed aluminum paste back surface field a 4 sq cm 50 micron m thick cell was fabricated from textured 10 omega-cm silicon which had an open-circuit voltage of 595 mv and amo conversion efficiency at 25 c of 14.3. the best 4 sq cm 50 micron thick cell (2 omega-cm silicon) produced had an open-circuit voltage of 607 mv and an amo conversion efficiency of 15. processing modifications are described which resulted in better front contact integrity and reduced breakage. these modifications were utilized in the thin cell pilot line to fabricate 4 sq cm cells with an average amo conversion efficiency at 25 c of better than 12.5 and with lot yields as great as 51 of starts; a production rate of 10,000 cells per month was demonstrated. a pilot line was operated which produced large area (25 cm) ultra-thin cells with an average amo conversion efficiency at 25 deg of better than 11.5 and a lot yield as high as 17