The electric power industry is facing unprecedented transformations and challenges with the implementation of the smart grids. This new grid paradigm has arisen to build a flexible electric power system that better coordinates energy resources and loads aiming at efficiently delivering sustainable, economic and secure electricity supplies. As a part of the smart grids (SGs), microgrids (MGs) have been developed to exploit the full benefits from the integration of distributed energy resources, especially distributed renewable generation based on variable and intermittent sources, such as wind and solar. Nevertheless, meeting all these goal requires the implementation of innovative energy storage technologies integrated with high efficiency and very fast response electronic power conditioning systems to interface with the electrical grid. Power electronics systems play a key role in regulating the raw energy from energy storage systems (ESSs) and connecting to the electrical grid. Hence, this paper performs a comprehensive analysis of major technologies in electrical energy storage systems and their electronic interface for applications in smart grids. The work provides a complete study of the technology profile of both energy storage and power electronics suitable for applications in the evolving grid.