The integration of distributed sources has a number of advantages, such as reduction of line losses, improved network flexibility, sustainability of energy production and minimization of investment in the existing network during capacity expansion. The stability of power grids remains the most important factor in the integration, especially of renewable distributed energy sources. Energy storage technologies are considered an acceptable and necessary solution that guarantees smooth transitions from energy networks with conventional structures to deregulated systems with an integrated large number of renewable and distributed sources. The value of energy storage systems is well understood from a technical perspective. In this paper, the appropriate categorization is illustrated with respect to different power and energy ratings of energy storage technologies. Storage technologies in different categories are suitable for providing specific services to networks, ranging from dynamic support to energy management. A portfolio of different storage technologies needs to be deployed to provide different services, which benefits both networks and storage owners. The services provided by electricity storage tanks are peak load reduction, reactive power compensation, harmonic compensation, and provision of tertiary reserve. Adequate aggregation is required, so that small storage facilities at the distribution levels can help maintain stability and provide flexibility in their own territory, and offer dynamic support and energy transfer. The storage facilities will be put into operation near large distributed renewable power plants, thus solving the issues of renewable energy integration.