In order to carry out the maximum use of unstable renewable energy, progress of energy storage technology is indispensable. Hydrogen which is one of the storage media has a high possibility of becoming a leading energy career. Therefore we proposed the totalized hydrogen energy utilization system that consists of fuel cells, water electrolyzes, metal hydride tanks and their auxiliaries. Aiming at introducing this system into actual buildings, we have examined the simultaneously effective uses of electricity, hydrogen and cold heat, by experimental test systems and numerical analysis. To realize the optimal design of the hydrogen energy utilization system with renewable energy, we developed the numerical simulation code for the metal hydride tank with unstable hydrogen supply. Furthermore photovoltaic-water electrolyzer(PVWE) system was manufactured. This PVWE system can follow the maximum power point of PV according to weather conditions, and can product hydrogen efficiently. Using this PVWE system, we got the hydrogen production pattern on the several weather conditions. These supply patterns were obtained using the mass flow controller. The characteristics of metal hydride tank with unstable hydrogen supply were investigated by experiments and simulations. Under the condition of unstable hydrogen supply, it was experimentally verifiable that the metal hydride tank can be stored stably. Also the validity of the simulation code was checked as compared with the experiment results. The simulations show the relations between the circulation water condition and the metal hydride tank situation.