The expansion of distributed renewable energy units drives the existing distribution grids to the limits. One possible solution to avoid exceeding the grid limitations is the integration of decentralized storage and conversion technologies that enable a decentralized coupling of existing energy supply infrastructures (electric-, gas-, and domestic heating grid). This paper presents the work and selected results of the project “Symbiose”, which examined whether the integration of decentralized storage and conversion technologies can support the massive integration of renewable generation into the electrical distribution grid. The idea of “Symbiose” was applied on two distributed model regions (urban and rural) with complete consideration of their regenerative potential. In order to examine the importance of distributed storage and conversion technologies regarding the technological requirements of the electrical grid a linear optimization model in GAMS was implemented. The optimization model comprised all three networks with predefined generation and demand elements, and variables of storage and conversion units. The objective function of the optimization model was minimal costs of the implemented energy system. The optimization results showed a violation of electrical network limitations with the installation of the region’s complete regenerative potential. Therefore storage technologies were considered in both model regions. The storage demand was reduced when a coordinated reactive power control was applied. Great reduction of the storage size was achieved by allowing the curtailment of electricity from renewable sources. The preferred storage technologies from a technological perspective were decentralized short-term storages (batteries).