small wind

Small wind turbines can range in size from 600W upwards to 20kW. A 600W sized machine will have a rotor diameter of around 2m increasing to 10m for a 20kW turbine. The majority of small turbine systems are mounted on a freestanding tower 10m to 30m in height.

The output (hence payback) of wind turbines varies significantly depending on a sites average wind speed, the nature of the site (i.e. urban, rural), its proximity to large obstacles and its height. The power output is proportional to the wind speed cubed so even a small increase in wind speed can have a dramatic increase on a turbines performance.

Turbines work best well away from surrounding obstructions, so you get a nice smooth airflow. Ideally you should site your turbine in the windiest possible location. As a general rule the turbine should be placed away from any obstacle such as a building or tree at a distance of at least 10 times the obstacles height or on a tower 2 times the height of the obstacle. Some small turbines (~1-2kW) can now be fitted directly to a building however, turbulent airflows around buildings can reduce their output markably. Therefore, if you have the space a turbine is almost always likely to perform far better mounted on a tower rather than a building.

The main issues in choosing wind power relate to planning permission, which can become onerous if your tower height exceeds 7m. A small 1kW tower mounted turbine will cost around £3,000 to install. A bigger 15kW machine will cost between £30,000 and £40,000. This includes the cost of towers and inverters but excludes the cost of foundations, which will vary by site, and of connecting to the grid. Grant money is available.

We do preliminary turbine sizing and cost benefit analyses for your site as part of our site assessment services.