Abstract: A system and method for creating capacitor-based electrical energy storage modules and electrical energy storage systems assembled therefrom. Submodules having a plurality of capacitors capable of storing electrical energy are used in different combinations to create electrical energy storage modules. Preferably, a number of submodules are placed into an enclosure or cabinet, whereafter the submodules are placed in electrical communication. The number of submodules installed in an enclosure is determined by the power output desired, and the space constraints of the area in which the enclosure will be located. One enclosure of one or more submodules, or a plurality of interconnected enclosures of one or more submodules, may form an electrical energy storage module. The module may be designed to output either DC or AC electric power, and may be equipped with a power conversion system and/or communication and control electronics to control the charging and discharging thereof.