The towers are mostly tubular and made of steel, generally painted light grey. Some towers are made of concrete. The blades are made of glass-fibre reinforced polyester or wood-epoxy. They are light grey because this is the colour, which is most inconspicuous under most light conditions. The finish is matt, to reduce reflected light.

Large modern wind turbines have rotor diameters ranging up to 65 metres while smaller machines (around 30 metres) are typical in developing countries. Towers range from 25 to 80 metres in height.

The blades rotate between 50-15 revolutions per minute at constant speed. However an increasing number of machines operate at variable speed.

When the wind stops blowing, electricity continues to be provided by other forms of generation, such as gas etc. Our electricity system is mostly made up of large power stations and the system has to be able to cope if one of these large plants goes out of action.