Abstract: An impeller for wind turbines comprises a rear ring having a central axis. The impeller comprises a front ring having an inner peripheral surface. The front ring is arranged coaxially and is slidably associated with the rear ring. The front ring is movable along the central axis and switches between a close configuration and a spaced apart configuration, with respect to the rear ring. The impeller comprises a plurality of blades connected to the front ring and defining a variable-pitch propeller. The blades being adjustable between a minimum pitch when the front ring is in the close configuration and a maximum pitch when the front ring is in the spaced apart configuration.