While a wind electric system can be a very efficient renewable energy system it's also very site specific, with a number of requirements that need to be met in order for a site location to be feasible. Often times, we think it's windier than it is and to make the most of a wind system sustained winds of 30-40 km/h are ideal. Generally, rural and remote areas are more suitable than urban environments. Best sites are homes on a hill, or near an ocean, with full south-east exposure to big, northwest winds and sheltered from trees, mountains or structures and other obstructions. A rule of thumb is that the wind system should be at least 20 feet taller than obstacles located within 200 feet of the tower.
How can you tell if you have a good wind at your location? There are a couple of ways. For the more serious wind enthusiasts we suggest purchasing an anemometer, which is a common weather station instrument used to measure wind speeds. They can usually be found at sailing or boating shops. Anemometers will measure the amount of wind on site, over a period of time.
You can get a general idea of a site feasibility without an anemometer, by generating a turbine formula through the Canadian Wind Energy Atlas, and filling it out using turbine data from a manufacturer (a list of manufacturers can be found on the Canadian Wind Energy Association's website at: www.smallwindenergy.ca).
In the "maps" section on the Canadian Wind Energy Atlas website, select "mean wind speed" and "30m," for residential installs, and then select your location tile, entering in your latitude and longitude specific postal code, to generate a turbine formula.
By filling out the formula with the max power, cut speed and rated speed data available from a wind turbine manufacturers' performance spreadsheet, you can determine the estimated energy output of a wind system for your location. In this example those numbers would be "5", "3" and "12" respectively.
Start-Up/Cut-In Speed: The wind speed at which a wind turbine will actually start to produce power. Wind speeds are often measured in meters per second, or m/s, and a good quality turbine should have a cut-in speed of around 3 m/s, or 3.6 kilometers an hour.
Rated Speed: Wind speed at which a wind turbine will produce its published amount of power. See “Average Power vs. Wind Speed” image below. Most turbines are approximately 10 to 12 m/s, or 35 to 40 km/hr.
Once this data is entered, a report for that location will provide annual energy output for a wind system at that site, and "use rate," or percentage of full potential of a solar wind turbine. According to the report generated for our example, below, the average annual energy output for a 5 kW turbine, would produce 12.01 megawatt hours a year. One megawatt hour is a 1000 kilowatts used or delivered in an hour, so this turbine would provide 12,010 kilowatt hours, or kWhs a year in ideal wind conditions. To check the amount of kWhs your home uses a year, check the monthly kWh average on your BC Hydro bill and calculate it over 12 months.
* The estimates generated from this formula may be higher than in reality, as they will not take into consideration various obstacles around the location. An anenometer will produce more accurate results.