Wind turbines are an effective source of renewable power in many areas across the world. To make sure a small wind system is right for you, there are some important initial points to consider:
Start-Up wind Speed
This is the wind speed at which the turbine starts turning by the wind. It should spin smoothly and easily when turn it by hand, and keep spinning for a few seconds. A good design can start spinning in a wind speed at 1 and 2 Meters per second (Between 3.6 and 7.2 Kilometers per hour)
Cut-In wind Speed
A wind generator can start rotating run in slow wind speed but it does not supplying power into the battery bank or system until the generator voltage gets higher than the battery bank or system voltage. Higher shaft speed means higher voltage in all generators . Normally the wind generators cut in at 3 and 4 Meters per second (Between 10.8 and 14.4 Kilometers per hour)
The area having the wind speed less than 4 Meters per second is not suitable to fit wind turbine .
Please note that winds decrease the closer they are to the ground. However the wind speed will increase with the increase of tower height but the cost of the tower will be more.
Best idea is to mount a wind turbine on the roof top
Rated wind speed
As the wind speed rises above the cut-in speed, the level of electrical output power rises rapidly as shown in the picture. However, typically somewhere between 11 and 13 meters per second (Between 39.6 and 46.8 Kilometers per hour)
The power output reaches the limit that the electrical generator is capable of.
This limit to the generator output is called the rated power output and the wind turbine and the wind speed which it is reached is called the rated output wind speed.
At higher wind speeds, the design of the turbine is arranged to limit the power to this maximum level and there is no further rise in the output power. How this is done varies from design to design but typically with large turbines, it is done by adjusting the blade angles so as to to keep the power at the constant level.
The ideal position for a wind power generator is a flat open space with good wind from at least one direction (known as the prevailing wind direction), a coastline, or a smooth hill top with an open area in the prevailing wind. The wind speeds up significantly near the top of the hill and the air flow should be reasonably smooth and free from excessive turbulence.
Excessive turbulence or “bad wind” causes fatigue damage and shortens a generator’s working life. When siting, keep away from local obstructions such as large trees and houses, or use a taller tower to ensure that the generator is well above the obstructions. Wind speed also increases with height so it is best to have the generator as high as your zoning laws and investment payback will allow. It is recommended to site you generator at least 6 m (20 feet) above any surrounding obstacles such as trees or buildings in a 76 m.
Components such as taller towers and running large amounts of wire more than 150 metres from your site can add significant costs to your wind system. You will need to balance power achieved in the best wind site over the cost of installation to determine the best overall placement of your system.
Typical siting Considerations
Coastal or Lakeside
Very strong prevailing winds typically blow from the ocean. If this is the case, it is very important to install your wind generator as close to the coastline as possible. Trees and taller structures can be down-wind from the wind generator.
Wind compresses as it blows over the top of a hill, increasing the wind speed. With proper placement, you may be able to use a shorter tower. We never recommend anything shorter than 10 m (33 feet). It is important to follow the general rule; that is the tower must be at least 6 m (20 feet) above any surrounding object.
Winds may be very turbulent running off a cliff causing wind shears. It is important to site the generator far enough from the cliff to avoid turbulent wind.
How to connect and use turbine power
OFF-GRID WIND POWER SYSTEM
A basic wind power system will consist of:
- Wind turbine on top of a tower (1) that is wired down to a control box (2) that regulates the charging of a large deep cycle battery bank (3).
- An inverter (4) which draws electricty from the battery bank and converts to normal household electricity (AC) and feeds the appliances in the home with power as needed.
- Various safety devices like fuses, breakers and lightning arrestor
On-Grid (Grid-Tie) Wind Power
A grid-tie wind power system can have almost exactly the same components as the off-grid system except that inverter is a special inverter which connects directly into the public utility grid.
Increasingly, there are also systems which don’t use a battery bank at all – the electricity flows directly from the wind turbine into the special ‘grid-tie’ inverter and then into the grid. These battery less grid-tie systems have the added advantages that they tend to be less expensive (no batteries to pay for) and more efficient (because the electricity doesn’t have to pass through the battery bank first). On the downside, if there’s a blackout then your wind turbine system will also shutdown and not be able to provide power to your home or business.