ELECTRICAL ENERGY SYSTEM WITH FUEL CELLS

An electrical energy system includes a fuel cell, a high-voltage battery, a direct-current converter with electrical isolation arranged between the fuel cell and the high-voltage battery, and a mains charging device connected between the fuel cell and the direct-current converter, wherein the mains charging device contains a rectifier but no DC-to-DC converter with electrical isolation. A method for operating such an electrical energy system for a motor vehicle includes charging the high-voltage battery by using the rectifier to rectify a mains voltage and passing the rectified mains voltage on to the high-voltage battery via the direct-current converter arranged between the fuel cell and the high-voltage battery.