With the increase in environmental energy and the development of renewable energies, their replacement in traditional electricity supply networks is unaffordable. This study designs a competitive power supply chain network considering two players (power plants and Distributed Generation (DG) units). Using DG units, users can produce their own energy. Also, this study shows the existence of refund policies for companies and users. Based on the buyback contract, users who own DG can determine their required electricity and, if necessary, purchase their required electricity from the power company or sell their excess production to it. The complex consists of biomass planting centers, suppliers, warehouses, power plants, DG units, ash sales centers, and finally electricity users. Raw materials (biomass) for electricity production by the power plant are purchased from customers or biomass planting centers and, considering ease of access, are transferred to the power plant location and, through a process in the power plant, are converted into the final product, namely electricity. The numerical results can be used as a reference for power plant engines or DG units.