Abstract: There is described a storage device configured to store energy at one or more given voltage levels. There is also described a storage circuit that may form part of a storage device and is responsible for storing electrical energy and discharging the electrical energy. And finally, there is described a modular circuit having a plurality of storage devices connected in series. The storage devices store electrical energy and provide a voltage level that may be switched in and out of the chain of storage devices in order to control an overall voltage level of the circuit. Each storage device may be individually protected from overvoltage while globally controlled for a given function.