china winddays wind energy co., ltd

1.How do residential wind turbines work?

A wind turbine, which is installed on top of a tall tower, collects kinetic (motion) energy from the wind and converts it to electricity that is compatible with a home's electrical system. In a normal residential application, a home is served simultaneously by the wind turbine and a local utility. If the wind speeds are below cut-in speed (7-10 mph) – the minimum speed to spin the blades - there will be no output from the turbine and all of the needed power is purchased from the utility. As wind speeds increase, turbine output increases and the amount of power purchased from the utility is proportionately decreased. When the turbine produces more ower than the house needs, many utilities institute a policy called “net metering” whereby the extra electricity is sold back to the utility. All of this is done automatically. There are no batteries in a modern, grid-connectedresidential wind system. Small wind systems for remote (off-grid) applications operate somewhat differently and often charge batteries so electricity is available when the wind isn’t blowing.

2.Will it help the environment if I install a wind turbine at my home?

Yes. Wind turbines produce no air, water, or thermal pollution and emit no greenhouse or smog-causing gases. By using wind power you will also be offsetting pollution that would have been generated by your utility company. Over its life, a small residential wind turbine can offset approximately 1.2 tons of air pollutants and 200 tons of greenhouse gas pollutants (carbon dioxide and other gases which cause global warming).

3.What makes a good wind site?

A good site for a wind turbine has ample wind and space to place a turbine.
WIND:? Winddays will begin making power at wind speeds as low as 3 meters per second (6.6 mph).? The turbine will continue to make power at increasing levels as the wind increases, but will automatically shut down when wind speeds get up to 25 meters per second (55 mph).? Typically, unobstructed, higher elevation areas comprise a better quality wind site.
SPACE: Depending on ground conditions, installation will require an area of between 350 and 600 sq ft. for the foundation and recommended clearance.? Generally it must be a location that is accessible by crane.? An electrical transmission infrastructure, if not already in existence, will need to be developed by your installer.

4.Is wind power the right choice for my application?

Factors to consider

·good wind resource

You can install an anemometer to determine your wind resource.? Some customers choose to install one for 3months and then project the annual wind resource from that.? Please note that even an anemometer installed for a full year will only measure the actual wind resource for that particular time period, and thus its accuracy for projecting future winds will still be burdened with some amount of standard deviation.

·home or business located on 1 acre or more of land

·average monthly electricity bills >$100 for 10kw system, >$50 for 5kw system

·zoning restrictions, economics incentives

5.How much energy will a 5kW turbine produce?

A 5kW wind turbine will produce different amounts of electricity based on the average wind speed at your site. winddays utilizes advanced turbine technology to ensure excellent energy capture for its size.?
There is a power formula

6. Do wind turbines make noise or interfere with TV reception?

Small wind turbines do make some noise, but not enough to be found objectionable by most people. A typical residential wind system makes less noise than the average washing machine. Small wind turbines do not interfere with TV reception.

7. How can I determine my payback?

You will need to provide three things:
• Your current cost of energy.? Our model allows us to input an average cost (per kilowatt).? You can get this information from your utility or figure it out from a year’s worth of utility bills.

• Your wind resource.? The amount of power you can make and your potential payback is a function of how much wind you have at your site.? We can input your wind data in “meters per second” or in “miles per hour.”?? See “How can I determine my wind resource” above for more information.
• The value of incentives available to you.? Is wind turbine dangerous to birds?

While no formal studies have been done, anecdotal evidence indicates that birds occasionally collide with small wind generators as they do with any other type of structure. However, such events are very rare.

8. Tower height?

Our standard towers are 9, 12 and 15m metres high. In general, the higher the tower, the higher the average wind speed that the turbine will experience, and it is normally the case? that a taller tower will generate sufficient extra energy to justify it's additional cost, especially if there are local obstacles to be avoided.

Compared to a 12m tower, a 15m tower may increase the annual energy by 15% and a 9m tower may reduce it by 15%. If however there are local obstructions, then the impact of changes in the tower height could be larger.

For sites where there are obstructions near the turbine, a tall tower may be needed to get the turbine above the turbulence created by nearby trees or buildings, as illustrated by the diagram to the left.

The taller the tower, the more the cost of the tower, the foundations and the installation, so you should not simply ask for the tallest tower that is available, but if the turbine is to be located near (< 200m) to surrounding obstacles, then a taller tower may be the best option.

Other factors, such as planning, may dictate the maximum height of tower you are able to install and some areas of the world.

Depending upon the type of the turbine, Iskra can offer either a free-standing tower, or a guyed tower.

• Guyed towers will tend to be used in rural locations, and have four guy wires going from the middle of the tower to concrete ground pads. They use slightly less steel than a free standing tower, but would not be considered suitable where people would be around the turbine a lot, as you don't want to risk damage to the guy wires.?

• A free-standing tower or "monopole" has no guy wires, but stands on a single concrete foundation with no other supporting structure. In many cases the choice is really down to personal preference, as to which one you prefer to look at.

10.How does it connect to the power grid?

The wind turbines generate power by rotating a permanent magnet generator which generates three phase AC at the frequency of the turbine's rotation. The AC power from the generator is not only the wrong voltage to be connected to the local power grid, but also, as the wind speed changes so does the rotational speed of the turbine, and therefore the frequency of the power generated. The power from the generator therefore needs to be converted to DC and then fed into a special electronic device called an inverter, to ensure that it is always at the correct frequency and voltage for the local grid.

Any power you generate will be first used by your own property, thereby saving you the maximum amount possible on your electricity bill. Any excess energy your wind turbine generates, e.g. on windy days or at night, is "spilled" to the power grid and your electricity supplier pays you for it.

In order to charge your electricity supplier for any energy that you export to the grid, you need to have a new bi-directional electricity meter installed which will work both when you buy (import) and sell (export) electricity. Depending upon your local requirements, there may be additional meters needed to record energy generation to enable a claim for a Government subsidy.

The inverter also provides essential safety features to control the power output from the turbine, and to automatically switch off the current if the grid connection should fail. This means that should the grid connection fail, the inverters will switch off their output and there is therefore no danger to any maintenance engineers fixing the fault. This does however mean that the wind turbine will produce no power to the property if the mains connection fails.