In this research the effect of variation of interest rate of each energy source on optimal results are investigated. This study presents an optimized design of Hybrid Power System in a distribution system including sources like, photovoltaic array, fuel cell and battery bank. In this study, an algorithm has been developed for evaluation and cost optimization Hybrid Power System. The costs include capital cost, replacement cost, operation and maintenance cost, fuel cost and production cost for Hybrid Power System and DG power during different load profile. Then an objective function with aim to minimizing of total costs has been considered. A genetic algorithm approach is employed to obtain the best cost value of Hybrid Power System construction.