Alvesta Wind Turbines

Wind Turbines - Factors Affecting Wind Turbine Choice

If you want to link up to the grid and want to generate more electricity than you consume then size of output is dependant upon your average power usage – which typically for most households is 500W – 700W  (this is not peak use which might be as high as 12kW). The above figure is the consumption averaged out over 24 hours.

As a rough guide wind generators are assumed over the year to generate 30% of their rated output so to produce a constant load of 700W you would need a 2.1 W generator. All of our turbines are suitable for grid tie connection.

* kW (kiloWatt) = 1000 watts: One 100-watt light bulb on for an hour, is 0.1 kWh (100/1000)

Choice of site is particularly important. Ideally you want a high average wind speed and low wind turbulence site. The power available varies according to the cube of the wind speed – so a 5 m/s wind generates double the amount of power that a 4 m/s wind does. The higher the average wind speed the better and generally a mean wind speed of at least 4.5 m/s is required. The lower the turbulence the lower the stress the turbine has to endure.

One advantage of the VAWT design of turbine is that it can operate in a confused air flow unlike HAWTs which need a clean flow of wind. The higher the turbine is positioned the higher the wind speed and the presence of barriers (trees, buildings etc) can alter the wind flow considerably and create a wake which extends downwind considerably beyond the barrier itself. Ideally:

A VAWT tower should be positioned at least 25 metres from the nearest building

A VAWT tower should be at least 6m high and 9m if there are wind barriers nearby

For safety reasons you should not allow anyone to come within 7m of the tower whilst the wind turbine is operating, or during windy weather

We do not normally recommend roof or gable mounting of wind turbines – they do vibrate and this will carry through the building and exaggerate noise inside the building.