Hybrid power generation systems for residential use that combined a polymer electrolyte fuel cell with a solar cell were evaluated in view of economy and environment. The performance of the fuel cell fed with hydrogen gas, the solar cell, and a water electrolysis apparatus were measured and used for the numerical analysis of the hybrid systems. The fuel consumption and the amount of CO_2 exhaust in an annual operation were calculated based on measured data of hourly electricity demand and monthly hot-water demand in many homes in all parts of Japan. The results showed that the fuel consumption and the amount of CO_2 exhaust of the hybrid systems can greatly decrease compared with the existing system with commercial electric power and city gas utilization for hot water.