Individual turbines vary greatly in their power output, from a few hundred Watts (battery charging systems for boats and homes) to 5 Megawatts (wind farm turbines connected to the National Grid). Small scale wind turbines, suitable of domestic or leisure purposes also vary in size with a range of models available, from less than 100 watts (W) up to 50 kilowatts (kW). Smaller, less than 100 W, microturbines, are often used to charge 12 volt (V) or 24 V batteries, for use on stand-alone systems. Turbines ranging from 0.6 kW to 50 kW can be used to provide electricity generation for individual buildings and homes.

Traditionally wind turbines have been free standing and mounted on a tall tower. However, a new breed of wind turbines are being developed specifically for the domestic market that can be installed directly on a building, usually on the rooftop or on the side of the building. Two configurations of wind turbine are being developed, the more common horizontal axis type and a vertical axis design.

Domestic wind turbine systems designed to generate electricity fall into one of two are two basic setups - stand-alone or grid-connected.

• Stand-alone systems

Small wind turbines have traditionally been used to generate electricity for charging batteries to run small electrical applications, often in remote locations where it is expensive or not physically possible to connect to a mains power supply. Such examples include rural farms, island communities, boats and caravans. Typical applications are electric livestock fencing, small electric pumps, lighting or any kind of small electronic system needed to control or monitor remote equipment, including security systems.

Small-scale turbines are ideal to this use and typically generate a direct current (DC) that needs to be connected to an inverter, to convert it to alternating current (AC). These systems also required a controller to ensure that the batteries do not become over or under charged. Any extra electricity will be diverted to other systems when the batteries are fully charged (for example to a water heater).

These systems are often accompanied by a diesel generator, which can be used for larger loads (for example welding) and also as a back-up, offering even greater efficiency and flexibility.

• Grid-connected systems

For grid-connected systems the output from the wind turbine is connected directly to the existing mains electricity supply. This type of system is most often used for wind farms exporting electricity to the electricity network but can also be used for individual domestic wind turbines.

The energy generated by a grid-connected turbine can be used to reduce the amount of energy taken from the grid, and for claiming Renewables Obligation Certificates (ROCs). In general, the value of avoided electricity purchases is generally significantly higher than the price obtained for any electricity exported to the grid.