Using renewable energy by integrating Energy Storage Systems (ESS) can serve to decrease energy production cost of Distributed Generators (DGs) as long as their operation is optimally managed. In this context, this work proposes the optimization of the energy production cost considering a two-level charging strategy for ESSs. For a 24 hours operation cycle, the optimization tries to reduce the total cost by minimizing the quantity of energy to be procured from the Distributed Generators (DGs) at each time period. Additionally, the objective is to determine the quantity of energy surplus generated by Renewable Energy (RE) to be stored in the storage system and determining the using of ESS by applying two levels for proper charging of the battery. The proposed formulation allows simultaneous optimizing DGs and REs, which interact directly when a strong increase in demand is present. In this work, the problem is modeled as a Mixed Integer Linear Programming (MILP) optimization problem. This approach is implemented under the GAMS 24.7.1 environment and is validated by using OSICPLEX. The given model can easily combine different sources of energy (renewables with battery and generators); by organizing the resources with high performance and flexibility. The optimization cost is implemented in a real case and the obtained results confirm the effectiveness of the proposed methodology.