Once you have reviewed the information on this web site, please use our free wind speed checker, and receive our free Getting a Turbine guide, which will explain in the detail the whole process, and give you an indication of the costs and expected energy generation.

We can get a reasonable estimate of the ‘windiness’ of a site from its location. The UK Government funded a database (NOABL) which gives an estimate of Annual Mean Wind Speeds (AMWS) in meters per second (m/s) for each 1km square all over the British Isles for a height of 10m.

Enter your post code in our free online Wind Speed Checker to see an estimate of the AMWS and estimated energy output, for a 1km square that includes your site.

Please note however that the wind speed checker only provides a very approximate method. The actual wind speed at your site will also be influenced by the local topography and any nearby obstructions such as trees, buildings etc. However, it will provide you with a useful indication of the possible energy capture from the wind turbine. Segen will advise you on the likely impact of your local conditions on your expected generation, but it can only every be estimated and should not be treated as an exact prediction.

In general, you need an AMWS of at least 5 m/s to be able to generate a reasonable amount of energy, and ideally more than 5.5 m/s.

The turbines that Segen sell work well at low wind speeds, but because the energy available in the wind is a function of the cube of its speed, there is very little energy available to be harvested at wind speeds less than 4 m/s.

The height of the tower can also have a significant impact as described on our Which Tower FAQ page.

Seasonal Variations Another thing to bear in mind is that there is normally more wind in the winter months than the summer ones. A wind turbine is therefore a very good match for heating and lighting requirements which are of course needed more in winter, but maybe not so well matched to air conditioning needs. The chart on the right gives an indication of how the amount of wind energy varies during the year at an average UK site, with typically 60% of the wind energy coming in the 6 months from October - March.
	Wind Direction In order for the turbine to be effective, it must have access to a good wind resource. This is one of the most difficult things to asses but in general the further away from buildings and trees, the better the average wind speed will be. This is especially true for any obstacles which are in a South West direction from the proposed turbine location, as that is the most common direction the wind comes from in the UK. This is illustrated by the “wind rose” shown to the left, showing the strength and amount of wind coming from each direction. As can be seen there is a dramatic difference between the amount of wind energy from the South West and the North East.
Hills and Valleys An important consideration is that of valleys and hills. Wind speeds up as it nears the top of a slope and slows down considerably on the other side of hill as it descends into the valley. The exact impact of this effect is very dependant upon the exact local conditions but the diagram to the right gives a good indication of the impact of this. This can have a dramatic effect on the energy that the wind turbine will generate. Taking the impact of the wind direction as described above, you should avoid locating a wind turbine on the North East side of a hill.
	Urban Environments Segen does not generally recommend a small wind generator in an urban environment as the AMWS in a town or city is likely to be substantially lower than in a rural environment and this will very significantly reduce the annual energy output. This is due to the cumulative impact of the buildings that may surround the wind generator causing increased drag on the available wind and possibly severe turbulence. See the Warwick Wind Trials web site for some real life wind speed measurements in urban environments.
Trees A large area of trees in the direction of the prevailing wind will also significantly impact the average wind available to a wind turbine. Shown on the right is an aerial photograph of what appears to be a clear area around a proposed location of over 200m, but the woods to the South and West will mean that the amount of wind will actually be much lower than hoped for and this site would not be recommended for a small wind turbine, unless the ground on which the turbine is located is much higher than the area of tress.

Wind Speed Measurement

One thing you can do is actually measure your wind speed with an anemometer, which simply measures the wind speed. When this is connected however to a data logger, you can collect and analyse your average wind speed over a period of time.

So why you might ask, do we not recommend doing this for every prospective site to obtain a more accurate wind speed?

The answer generally is that you would need to measure the wind speed for a period of at least 3 years to get a truly accurate average, as the wind speed not only varies during a year, but you can get “windy” and “calm” years, which can make a significant difference.

There are many DIY solutions available, including one from Better Generation for only £60, but to be genuinely useful, this will need to be mounted on a tower and not just attached to the side of your house. A more sophisticated system is available from Prodata (illustrated to the left), and whilst this is more expensive, at around £400, it provides many additional features that you might find of use.

The process of collecting, and analysing the data can be a complex and skilled process, and generally we would say is best left to an expert, as many adjustments need to made to cater for local conditions before any meaningful data can be produced. A company called Sustainable Energy Systems can provide an all inclusive measuring service for approximately £400 for three months, including the rental of the equipment and tower.

Solar Power Systems

Segen also provides a range of roof and ground mounted Solar PV Systems, which may be attractive if you do not have sufficient wind, space or location to make a small wind turbine viable. For more information on the solar photovoltaic systems we offer, please visit our PV Systems, Solar PV Siting and Solar PV FAQ pages to learn about what Segen could offer you.

Further Reading

A more detailed guide to the energy generation from wind generators can be found on the Danish Wind Energy Association's excellent web site, and this is well worth a read when considering your turbine. 

There is a good guide to Wind Resource Assessment for Small Wind Turbines on the web site of the Small Wind Industry Implementation Strategy's (SWIIS) web site.

A recent report by Environmental Change Institute, Oxford University Centre for the Environment, discusses Characteristics of the UK wind resource over the longer term.

The EU funded project WINEUR has its own web site containing many documents on urban wind for those considering such an installation.

You may be interested in reading an excellent article on Turbine Siting published in Homepower Magazine, written by the US wind power eminence Mick Sagrillo.