Hydrogenated amorphous silicon solar cells were fabricated by photochemical vapor deposition. A three‐separate‐chamber system was newly developed to reduce the contamination of the dopant elements as well as oxygen or water originated by the loading and unloading procedure. Wide optical band‐gap hydrogenated amorphous silicon carbide was prepared using acetylene (C2H2) for theplayer. The deposition conditions for each layer were optimized and the highest‐energy conversion efficiency of 9.64% was obtained. This high conversion efficiency was mainly attributed to the large short‐circuit current which indicated that the quality of theilayer is reasonably good.