These basic components include:
A rotor, consisting of blades with aerodynamic surfaces. When the wind blows
over the blades, the rotor turns, causing the generator or alternator in the
turbine to rotate and produce electricity.
A gearbox, which matches the rotor speed to that of the generator/alternator.
The smallest turbines (under 10 kW) usually do not require a gearbox.
An enclosure, or nacelle, which protects the gearbox, generator and other
components of the turbine from the elements.
A tailvane or yaw system, which aligns the turbine with the wind.
If you plan on building a horizontal axis wind turbine, you will need a tower on which to
mount the turbine (vertical axis turbines are usually built on the ground).
Several types of towers are available:
Guyed lattice towers, where the tower is permanently supported by guy wires.
These towers tend to be the least expensive, but take up a lot of space on a
yard. A radio broadcast tower is a good example of a guyed lattice tower.
Guyed tilt-up towers, which can be raised and lowered for easy maintenance
and repair.
Self-supporting towers, which do not have guy wires. These towers tend to be
the heaviest and most expensive, but because they do not require guy wires,
they do not take up as much space on a yard.
An important factor in how much power your wind turbine will produce is the height of
its tower. The power available in the wind is proportional to the cube of its speed. This
means that if wind speed doubles, the power available to the wind generator increases
by a factor of 8 (2 x 2 x 2 = 8). Since wind speed increases with height, increases to
the tower height can mean enormous increases in the amount of electricity generated
by a wind turbine.