Nacelle

- without gear

The nacelle on top of the tower contains the shaft, the generator, the cooling unit, the electronic controller and a yaw mechanism. The casing is mostly plactics, but there are some that are made of steel. Due to their larger ring generator, nacelles for gearless turbines have a larger diameter and are mostly round.

- with gear

The nacelle on top of the tower contains the low-speed shaft, the gear, the high-speed shaft and hydraulics system, generator, cooling unit, electronic controller and yaw mechanism. The casing is mostly plastics, but there are also steel nacelles. Due to the serial order of hub, gear and generator, turbines with gear usually have an elongated form.