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Frequently Asked Questions

Here are some of the most commonly asked questions about small wind energy systems.

Just as there are frequently asked questions about wind turbine technology, there are some common misconceptions. Read the top myths about wind power and make sure you have got your facts straight.

Have your own turbine
Can I have my own wind turbine?
How do I find out if my site is windy enough?
How does a wind turbine make electricity?

Turbine details
What size turbine will I need?
How tall are small wind turbines?
How much space do I need for a turbine?
Do I need planning permission?
What are wind turbines made of?
Can I build my own wind turbine?

Issue to consider
Are wind turbines noisy?
Do wind turbines affect radar systems or TV reception?
Will small wind turbines have a 'flicker' from the turbine blades?
Will small wind turbines affect birds?
What about lightning strikes?

Electricity generation
Can I use my turbine for heating?
Can I connect my turbine to the grid?
How much of the time do wind turbines produce electricity?
What happens when the wind stops blowing?

Costs and funding
How much does a wind turbine cost?
Can I get a grant for my wind turbine?
Isn't it cheaper to save electricity?

Turbine lifetime
How do I look after my wind turbine?
How long do wind turbines last?
Can the turbine be re-sited?

Can I have my own wind turbine?
Small wind turbines are ideal for householders, communities and small businesses to use for on-site energy generation. There are a range of different types of small wind turbine models, and thanks to their flexibility, small wind turbines can be installed in most locations. Your individual site specifics (such as location, wind speed and local landscape) will eventually determine the best turbine type and size for your case.

How do I find out if my site is windy enough?
SUREnergy can help you determine the average wind speed in your area. The actual wind speed at your site will be influenced by the local topography and any nearby obstructions such as trees or other buildings. Wind movement around buildings themselves is very fickle, so take expert advise as to which option is best for your site. A fixed to buildings rather than free standing on a tower or mast. A site with an average wind speed of 4-5 meters per second is generally sufficient enough to make installing a small wind turbine worthwhile.

For urban areas, please contact the manufacturers in order to establish wind speeds in your area, since there are likely to be other factors affecting wind speed such as the structure and height of buildings.

How does a wind turbine make electricity?
Most wind turbines have three blades which face into the wind; the wind turns the blades round, this spins the shaft, which connects to a generator. A generator produces electrical energy from mechanical energy.

What size turbine will I need?
An average house uses an estimated 4,700 kilowatt hours (kWh) of electricity per year. To find out how much a wind turbine produces, go to our calculations page to see energy production and emission saving calculations. Note however, that the generation from a wind turbine and the demand in a house are not coincident. If the wind turbine is connected to your side of the utility meter, you will use all the wind power available to meet your demand. When the wind generated power is greater than your demand, the excess is exported to your local network. You are permitted to sell that excess to a Supplier under terms arranged with that Supplier. Export metering measurement will be needed, but this need not be at short intervals (e.g. half hourly) and may be annual. However, generally, the meter reading charge is large, ~ £50, and so at least about 5,000 kWh/year of exported electricity will be expected before earning sufficient to cover more than the meter reading charge.

  • 1.5kW turbine will produce an average 3,942 kWh per year, saving 3,390 Kg of CO2 emissions each year.
  • 5kW turbine will produce 13,140 kWh per year, saving 11,300 Kg of CO2 emissions each year.
  • 15kW turbine will produce 39,420 kWh per year, saving 33,900 Kg of CO2 emissions each year.

Manufacturers will usually assess the power requirements and likely wind generation of your particular site to see which of their turbines may suit your needs. You may wish to have independent advice from a colleague, but as yet there is no general agency for this.

How tall are small wind turbines?
Tower height varies according to wind turbine models, but generally range from 6 to 12 meters for stand-alone machines, which are often used to provide a power source where grid power is not available. In general, the higher the tower, the higher the average wind speed that the turbine will experience and the smoother the wind. The rotor diameter of small wind turbines ranges from 1.0 to 11 meters depending on the type of a model.

How much space do I need for a turbine?
Ideally, stand-alone turbines should be sited as far away as possible from buildings or trees, which may block the wind and cause turbulence. As a guide, the wind turbine should be about twice the height of obstructions in the immediate front of it (for at least the prevailing wind direction). In general, the turbine should be above the height of nearby obstructions that are within a distance of 10 to 20 meters of the tower heights. See also our fact sheet on siting a wind turbine.

Rooftop-mounted turbines can generally be mounted on either the side or on top of buildings and should be installed so that the vibrations from it will not be transmitted to the building. Local turbulent airflow around the building, which causes reduction in generated output and could damage the turbine, must be considered as well. In general, the less turbulent and varying the wind, the better the wind power generation. A horizontal axis turbine that is frequently changing direction will have its generation seriously perturbed.

Do I need planning permission?
Small wind energy installations may require planning permission and you should always consult the planning officials, preferably confirmed in writing if this is needed. It is clearly good manners to discuss your plans and aspirations neighbours. Relevant factors include environmental impact, access to the site, noise and visual effects. Overall, national planning policies support the development of small scale wind energy.

What are wind turbines made of?
Wind turbine towers are generally made of steel. The blades are made of glass-fibre reinforced polyester or wood-epoxy. The finish in most models is matte to reduce reflected light.

Can I build my own wind turbine?
There is a very good book on this subject, 'Wind Power Workshop' by Hugh Piggott, available from the Centre for Alternative Technology. However, as with all technical and potentially dangerous equipment, most people should buy commercially manufactures and professionally tested machines.

Are wind turbines noisy?
The majority of modern small wind turbines have been designed to be very quiet, for instance by having direct-drive systems to avoid gear box noise and to increase efficiency. In general, the wind itself makes more noise than a wind turbine. It is most unlikely that any niose from small wind turbines will be heard at more than 50 m.

Do wind turbines affect radar systems or TV reception?
Small wind turbines are unlikely to have any detrimental effects on aviation and associated radar or navigation systems. In general, turbines with small diameters are unlikely to have effects on television and radio reception. If this occurs, it is likely to be highly localised and technically easy to overcome. It is also unlikely that small rooftop wind turbines will effect either mobile phone reception or fixed radio or microwave communications links.

Will small wind turbines have a 'flicker' from the turbine blades?
Potentially, sunlight passing through moving blades can cause a flickering effect in 'line of sight' directions. The possibility of the shadow from the wind turbine causing flicker should be considered at the site selection stage. It is normally possible to avoid this problem. Reflections from the blades are unlikely, especially as the coatings used on modern turbines have been selected to minimise reflection.

Will small wind turbines affect birds?
Experience and careful monitoring by independent experts shows that birds are unlikely to be damaged by the moving blades of wind turbines.

What about lightning strikes?
Lightning strikes do occur and can cause damage to any structure raised from the ground. However, lightning protection is a well-known practice and can be applied to wind turbines as for other equipment. On some turbine models, full protection of electrical circuits is installed at manufacture. Obviously, as with other elevated structures, protection against lightning is advisable if the turbine is installed in an area where lightning strikes are frequent. Insuring the turbine against lightning damage may be a wise precaution.

Can I use my turbine for heating?
The simple answer is yes, small wind turbines can be used for direct heating, e.g water heating as well as for battery charging and they are also ideal in remote off-grid locations. However, the energy required to heat a building is usually significantly more than the energy used in electricity, so a much larger turbine would be needed for building heat.

Can I connect my turbine to the grid?
Small wind turbines can be connected to the local electricity network and the total electricity they generate is eligible for Renewables Obligation Certificates (ROCs) under the Renewables Obligation (i.e ROC income can be obtained from both the electricity you use on site and that you export). The value of a ROC is now (2006) about 4.5 p/kWh. When a wind turbine connection to the mains supply is made, it has to be approved by your local electricity distribution utility. This company will require the connection to be of a satisfactory technical standard. Therefore, the cost of incorporating power import and export metering and approved electrical protection equipment may be a significant proportion of the total cost, i.e. perhaps about 10% or more. The company may also limit the electrical capacity of the wind turbine that may be connected to a particular distribution line, depending on the loading of the electrical distribution system in the vicinity.

How much of the time do wind turbines produce electricity?
A modern wind turbine produces electricity 70-85% of the time, but it generates different outputs dependent on wind speed. Over the course of a year, a small wind turbine in the UK will generate about 20% to 30% of the amount it would generate in a constant strong wind. This is known as its 'load factor' (or 'capacity factor'). The turbine itself has usually at least 97% mechanical availability and generates with 95% mechanical to electrical efficiency, so the limited output is overwhelmingly associated with lack of wind. The load factor of conventional UK thermal power stations is on average 50% and the mechanical to electrical efficiency is between 30% and 50% depending on the type of plant.

What happens when the wind stops blowing?
When the wind stops blowing, electricity continues to be provided by other forms of generation in an isolated system (e.g. batteries, diesel generator) and by the grid in a grid-connected system. UK electricity generation is now overhelmingly from large power stations and so the system has to cope when one of these large plants goes out of action. Consequently, it is possible to have at least 10% to 20% of the country's electrical demand met by intermittent energy sources, such as wind energy, without having to make any significant changes to the way the system operates.

How much does a wind turbine cost?
The price of small wind turbines depends on the size and type of a model you buy. Generally speaking, the Government's Clear Skies grants programme estimates that typical small system costs are $2,500 - $5,000 per kW capacity installed. The rooftop turbine market is still in the early stages of development, but manufacturers estimate that once mass production starts, an average 1-1.5 kW model will cost around $1,000 per kW capacity installed. The cost of large, megawatt scale, wind turbines is today about $800 per kW capacity.

Note that customers installing a domestic turbine at an existing house qualify for a reduced rate of VAT at 5% and, presently, for government grants (explained below).

Can I get a grant for my wind turbine?
In England, Wales and Northern Ireland, the Government's Clear Skies programme offers grants for households and communities. Grants are offered for $1,000 per kW installed up to a maximum of $5,000. The minimum size of installations under this scheme is 0.5 kW. Installations larger than 5 kW are allowable, but capacity above that level will not receive a grant. For more information visit Clear Skies. Note that this programme will be replaced by Low Carbon Buildings Programme in April 2006. The Scottish Community Renewables Initiative (SCHRI) applies in Scotland.

Isn't it cheaper to save electricity?
Since most of us are not fully efficient in using energy, it is almost certainly cheaper to reduce electricity consumption than to buy it or generate oneself. The latest information on how much it costs to save electricity is available from the Energy Savings Trust. Nevertheless, electricity generation is necessary. Therefore, to combat climate change and to have security, it is essential both to increase the proportion of renewable energy and also to have energy efficiency.

How do I look after my wind turbine?
The maintenance required for small wind turbines is likely to be minimal. An annual check is all what is likely to be required and can be arranged by the wind turbine manufacturer.

How long do wind turbines last?
A wind turbine typically lasts around 20 years. During this time, some parts may need replacing. The very first factory-mass-produced turbine celebrated its 21st birthday in May 2001. The Vestas 30 kW machine has operated steadily throughout its lifetime, and so far, none of the major components have had to be replaced. Some earlier workshop-produced turbines have operated for longer.

Can the turbine be re-sited?
Yes, provided the new site is suitable. Costs will be incurred to dismantle the turbine, transport it to the new site and re-install it. An estimate of these costs can only be prepared after a survey of the old and new sites.


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