A wind or water energy installation for generating electrical energy, an installation having at least one propeller and at least one generator including at least one rotor, at least one stator and at least one magnetic circuit generating a magnetic flux. The at least one magnetic circuit has at least one magnet on the stator side and at least one coil on the stator side, through which at least part of the magnetic flux of the stator-side magnet flows, and the magnetic circuit is closed by the rotor which has a magnetic resistance (Rm) dependent on its respective rotational angle, on its surface facing the stator, such that the size of the magnetic flux in the at least one stator-side coil depends on the respective rotational angle of the rotor and changes when the rotor rotates.