The conversion efficiencies of 7.0, 5.5 and 4.7% have been obtained for ITO/n-i-p/SS a-Si: H solar cells with 1.2, 49.and 100 cm2 area under AM1 (100 mW/cm2) illumination, respectively. The short circuit current improvement by changing the cell structure from the ITO/p-i-n/SS to the ITO/n-i-p/SS is explained by the lower absorption coefficient of n-type windowside layer in the latter structure. The decrease of the fill factor with increasing cell area is mainly caused by the series resistance due to the ITO film and the grid electrodes and the contact resistance between the ITO film and the grid electrodes.