The insertion of distributed energy resources (DER) into the distribution grid has profoundly changed the structure of current systems. The inevitable presence of these new technologies requires the use of increasingly sophisticated simulation methods capable of dealing with the complexities added to the grid by DER. This paper presents an evaluation of the impact observed on the reliability indices of a distribution system with the insertion of DER, with emphasis on the modeling of energy storage devices. For this purpose, the quasi-sequential Monte Carlo simulation (MCS-QS) technique is implemented, capable of representing chronological variations in the grid, with low computational cost. A real system modified by the inclusion of DER is used in simulation and discussions.