The origin of the difference in the open circuit voltageVocbetween ap‐i‐nandn‐i‐ptype hydrogenated amorphous silicon solar cells is discussed theoretically, considering the interaction of photogenerated free electrons and holes, i.e., the effect of a self‐field. It has been clarified that the self‐field aids the carrier collection in ann‐i‐pcell whereas it impedes the carrier collection in ap‐i‐ncell. This difference in the effect of the self‐field on the photovoltaic process causes the difference inVocbetween these two type cells.