the min targets of otimization problem in the stand alone hybrid generation system is to satisfy the lead demand with high reliability and respect ti minimum annual cost of system. thus paper utilizes genetic algorithm (GA) method to determine the optimal capacities of hydrogen, wind turbiinesand microhydro unit according to the minimum cost objective functions that relate to these two factors. in this study, the cost objective functionn includes the annual capital cost (ACC) and annual custumer damage cost (ADC). the proposed method has ben tatsed in the hybrid power generation system located in sirengge village in central java of indonesia. simulation result show that the optimun configuratiom canbe achieved using 240 ton of hydrogen tanks,0 wind turbines and 3 X 2.1 MW of microhydro unit respectively.