This paper describes the application of a new iterative method to numerical calculation of the performance of amorphous siliconp‐i‐nsolar cells. Using this method, the effects of gap‐state density, dopant impurities (B and P), and various cell parameters (diffusion length, interface recombination velocities, thickness of theilayer, etc.) on cell characteristics are investigated. The calculated results show that a strong electric field advantageously effects cell characteristics (especially through fill factor) in thei‐layer where many photocarriers are generated. However, a uniform field isn’t always adequate for high conversion efficiency. The improvement in conversion efficiency provided by boron doping is attributed to stretching of the diffusion length rather than rearrangement of the field distribution.