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There are two methods you can use to measure your site's wind speed; one involves a detailed site assessment, while the second is based on modelled data. We explain more below. Measuring wind speed with an anemometer
The only way to know for sure what kind of power your turbine might produce before you invest in one is take some direct wind speed measurements. Definitely worth doing. There are companies around who can come and do a really professional site assessment, but for small machines, this could end up costing as much as the turbine itself! But you can do it yourself too with a gadget called an anemometer; a gauge for measuring the speed and direction of wind. Ideally, you'll use it to gather data over several months and seasons to get an accurate average wind speed. Decent anemometers are usually pretty pricey, so we've worked hard to bring you a low cost, accurate and easy to use anemometer called the Power Predictor. The alternative: modelled wind speed data
Alternatively, there are also ways of roughly estimating your wind speed using modelled wind speed data, but this needs to be taken with a pinch of salt.
One of the easiest ways to do access modelled data is by visiting the Segen website and typing in your postcode to get back the average wind speed (in metres per second) for your house. There is also a generalised wind speed map (at 50m above ground level) at www.windatlas.dk. The Carbon Trust have also recently launched an online wind speed estimator. The problems with modelled data
The figure you'll get from such modelled data will be the average for the square kilometre you live in. But there's always a lot of variation within each square km, and the information takes no account of the lower and more turbulent winds in urban areas. Have a think about where the turbine might be installed, and what might affect the wind flows. Here's a handy list of things to account for (from suggestions published by turbine manufacturers Proven Energy): - Take account of nearby trees and buildings
- A site at the bottom of a valley or hollow will have a lower wind speed than the average, so adjust the average wind speed down
- A site on top of a hill or knoll will have a higher wind speed than the average, so adjust the average wind speed up
- The modelling does not include the effect of sea breezes, so for coastal sites add 0.5 - 1 m/s to the wind speed
- For flat open countryside the model returns a more accurate result
- For complicated terrain the model is less accurate.
Read more. . . .
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