The disclosure relates to an electrical energy supply device having usage units, wherein each usage unit is designed to generate or to buffer electrical energy. The disclosure proposes that the energy supply device carries out an energy exchange through a busbar assembly, wherein busbars of the busbar assembly form a busbar matrix, and in the energy supply device the usage units are divided up into strands and in each strand the usage units are hooked up in a series circuit and the series circuit is connected across a DC voltage converter to one strand end of the strand and each strand end of the strand is connected across a respective galvanically separable switching unit.