Application Considerations

  • Small wind turbines usually have a cut-in wind speed of around 3 m/s and with rated wind speed of about 12 m/s or above. Therefore, small wind turbines are best located at sites with average wind speed greater than 5 m/s.

  • The process of deciding whether or not a site in Hong Kong is suitable for installing a small wind turbine depends to a certain extent on an informed judgment, due to the complex topography of the territory. The inhabitants at the location, or those familiar with the conditions of the location can be asked to provide a rough opinion about how windy the location is. The vegetation at the location can give hints about the wind conditions. The Wind Resource Maps section of this website can provide some reference figures. Without actual wind measurement, it would be difficult to get an accurate energy yield prediction, and it should be accepted that the actual energy yield will turn out to be much lower or higher than expected.

  • A more scientific approach to obtain an estimate of the wind resource of the site is to conduct short-term wind measurement (for at least three months, with full-year measurement more preferably) at the location where the small wind turbine is proposed to be installed, and correlate the gathered short-term data with a reference station with long-term data, to obtain the long-term wind resource parameters.

  • Take note of shading effect by nearby structures such as buildings and trees. Generally speaking, the more exposed the location to the easterly wind, the better will be the wind resource.

  • For standalone applications, wind/solar hybrid system with battery storage can provide more reliable power supply as the two RE resources supplement each quite well and there may be prolonged periods without one of the resources.

  • As Hong Kong is subject to typhoons, choose among the strongest wind turbines available in the market. Manufacturers of small wind turbines usually quote the "survival wind speed" for the wind turbine in the technical specifications. Some small wind turbines have survival wind speeds in the range of 55m/s to 65m/s. (The IEC 61400-2:2006 adopts wind turbine classes similar to those for large wind turbines, and describes the term "survival wind speed" to be a "less precise term" given in "popular language".) For some turbines with lower survival wind speeds, the manufacturers may recommend pulling down the wind turbine during typhoon conditions. Pulling down the wind turbine may pose many issues such as skills and safety.

  • Another way to choose a small wind turbine suitable for operation in locations with typhoons is to look for ones that have actually been used in such locations for a number of years, successfully without failure due to typhoons.

  • Take note of the overspeed control mechanism of the turbine. The furling process may be noisy during high wind conditions.

  • Take note of lightning protection issue. Ask the manufacturer about lightning protection requirements for the wind turbine. For properly designed wind turbines, lightning protection is achieved by connecting the grounding terminal of the wind turbine to a proper grounding system, and if necessary, adding surge arrestors at the power output terminals to protect the battery charging unit or the inverter.

  • Take note of possible need to submit plans for the approval of the Building Authority under the Buildings Ordinance. If mounted on the roof of a building, take note of structural strength of the mounting arrangement, and take note of the vibration and noise issues. Safety aspects should also be considered.

  • There are wind turbines specially designed for rooftop applications (e.g. This web page has hyperlinks which may transfer you to third-party website.SWIFT of UK, This web page has hyperlinks which may transfer you to third-party website.Turby). However, such products may not be available to Hong Kong.

The Small Wind Turbine - Literature section provides some links to useful references about siting of small wind turbines, in particular the one available on the Small Wind Industry Strategy website.

   
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