The power generated is proportional to the cube of the wind speed, which means that doubling the wind speed gives eight times as much power. Conversely, if the wind speed halves, you’ll only get an eighth as much.
To get the best from a turbine you need to put it where it will receive the strongest possible winds. An ideal site is a smooth hilltop with a clear open stretch (at least in the prevailing wind direction). This is why turbines are rarely sited in towns. Wind speeds increase significantly with height, so it makes sense to mount a turbine very high up. Most turbine suppliers provide poles or towers (often several metres high), and the additional cost should be repaid by the extra energy generated. A tower helps to avoid the turbulence created by obstructions such as buildings and trees – this turbulence reduces power output and increases wear and tear on the machine. Click to enlarge the diagram below.
The installation of a wind turbine requires planning permission, as it will be above the level of the house and will create a small amount of noise. Because of this it’s sensible to talk to your neighbours about your plans – people will generally be more supportive if they are consulted before a planning application goes in.