The global energy markets of the last decade have been characterized by an ever-increasing share of electric power, more than half of which is projected to come from renewable energy sources by the year 2030. Such a remarkable rise in the quantity of renewable energy, of course, will induce a series of related changes as, without the successful integration of all that unconventional type of energy into the existing energy systems, the sustainability and security of the electricity supply cannot be maintained. As a result, new legislation and energy policies are required all over the world to accommodate not only the latest technological solutions but also a variety of previously unknown market actors. In the institutions, businesses and households of Hungary, the notion of sustainability has been gaining more and more importance lately, which is manifest in the efforts to reduce the use of electricity from the public grid, which is generated by burning fossil fuel. This endeavor is facilitated by the installation of photovoltaic (PV) household-sized power plant (HMKE) systems. Currently, the Hungarian electric energy system does not possess sufficiently flexible capacities; moreover, even this capacity is expected to decrease considerably in the future due to the phasing out fossil fuel power plants. Furthermore, dynamically growing HMKE penetration means an increasing frequency of technical problems in the macroenergy system (e.g., reverse energy flow in the local grid). It is such challenges that energy storage technologies can provide a solution for. Presently, there is insufficient information available on the recommended energy storage size necessary for the efficient integration of Hungarian HMKE systems into the electric energy system and the related investment needs. The innovative novelty of this study is that it examines the quantity and power of Hungarian HMKEs in the districts of the various electric companies over time with a view of exploring a possible way of their efficient integration into the electric energy system by determining the nominal energy storage power and energy capacity of the proposed energy storage systems. In addition, the paper also presents the expected investment needs associated with these energy storage systems.