The invention relates to a control for an electrical energy supply unit, comprising a first filling level input, to which a first filling level of a first energy store of the electrical energy supply unit can be transmitted. In addition, the control comprises a further filling level input, to which a further filling level of an optional further energy store of a further electrical energy supply unit can be transmitted. Furthermore, the control comprises a nominal alternating voltage determiner which is designed to determine a nominal alternating voltage while taking into account the first filling level and/or the further filling level. In addition, the control comprises a nominal alternating voltage output, from which the nominal alternating voltage can be transmitted to an alternating voltage generator of the electrical energy supply unit. An electrical energy supply unit comprises a control according to the invention, a first energy store and an alternating voltage generator having a first and a second terminal. The first terminal of the alternating voltage generator is connected to the first energy store in an electrically conductive manner. The alternating voltage generator is designed to generate at the second terminal an alternating voltage that corresponds to a nominal alternating voltage. An electrical energy supply system comprises an electrical energy supply unit according to the invention and at least one additional electrical energy supply unit according to the invention, which are connected to one another in an electrically conductive manner.