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	The sight of wind turbines around the UK is not an uncommon one but it is only lately that domestic wind power is being more seriously considered. The UK accounts for 40% of Europe's wind energy but this is largely untapped with only about 2.2% of our electricity currently generated by wind power. This lags well behind many other European countries some of which generate 20% of their electricity from wind. Domestic wind power is another way of harnessing this energy thus helping the environment and saving money. Wind turbines use the wind's lift forces to turn aerodynamic blades that turn a rotor which creates electricity. Open, high, flat areas are best suited to wind turbines but they can also be used to provide domestic wind power on a smaller scale than those we see dotting the landscape. It is worth looking into the wind in your area, however, and the NOABL database contains information on local wind speeds. Go to the Go to the www.renewable-uk.com website for more information. It should also be noted that domestic wind turbine installations usually require planning permission.
In order to fully power a modern home, the domestic wind turbine would need to span five metres from tip to tip on a site with good wind conditions. The average household consumption is approximately 4500 kWh and a domestic wind turbine with a span of two metres might yield 500 kWh per year in good conditions. The energy produced by the turbine can be used to charge batteries or be connected to the national grid. In many cases homeowners use a domestic wind turbine to supplement the energy they receive from the national grid, thus reducing their bills but not being entirely reliant on the wind power. Small scale wind power (blades less than 2m diameter) generate from 300 W – 1.5 kW. At this size to use them for heating it is not practical, however to use these small units to heat hot water on DC voltage could be viable without using an inverter to convert the power to AC voltage. Extra low DC Voltage immersion heaters can be obtained for 12, 24 & 48 Volt systems.
In order to prevent the heating element from receiving fluctuating over-voltages a small battery should be used as a buffer between the wind turbine output and the heating element for example a 12V motorcycle battery is perfect for this task (for 12V immersion elements) - no more powerful than 4 amp hours / 50 cold cranking amps, and it should be a lead-acid battery which can be refilled with water. A sealed gel type battery or dry cell should not be used. The heating element chosen must be closely matched to the typical power output of the wind turbine. If the element is too large (high wattage), the wind turbine will not be able to start up spinning unless the wind is very strong. If the element has a low wattage, nothing will be damaged since the small battery will limit the voltage to around 12V, but heat will be dissipated in the wind turbine generator and cables rather than used to heat water. If the heating element is poorly matched then there is the risk of a large voltage drop between the wind turbine generator and the immersion heating element causing the cable between them to melt. In this eventuality the wind turbine would then freewheel at very high RPM and could easily be damaged or destroyed.
Because the wind speed is of crucial importance to the performance of the generator, it is a must that the wind speed is greater than 4m/s. The chart below is an example of a 1000W wind turbine.

Parameter	Details
Nominal Battery Voltage	24 or 48 VDC
Grid-Tie Capable	Via LE Grid Tie Inverter
Rotor Diameter	1800mm
Rated Wind Velocity	8m/s
Rated Output	300 watts
Max Output	1000 watts
Rated RPM	410
Start-up Wind Velocity	1.5-2m/s
Total Weight	54kgs
Tower Mount	88.9mm Outer Diameter Tube
Chassis Construction	Laser Cut Steel
Rotor Blades (3)	Glass Reinforced Nylon

Parameter	Details
Rotor Diameter	6.0 metres
Rotor Type	3 Blade Downwind
Blade Material	Glass Reinforced Composite
Rated Output	5000watts at 11m/s (24mph)
Peak Output	6000watts
Cut-in Speed	3m/s (6.7mph)
Estimated AEP	7,000-20,000kWh per year Depending on site location and wind
Weight	265kg
Generator Type	3-Phase Brushless NIB Dual Rotor Out-runner PMA
Grid Tie Equipment	SMA WB6000
Control	Flight Computer, Auto Shut-Down, Over Voltage, Mechanical Brake.
Acoustic Levels (at 30m)	53dB(A) - Equivalent to normal speech
Lifetime and Servicing	20 Years Annual Inspection Recommended
Warranty	2 Years

The most useful wind turbine for the Heating Engineer is one that will generate about 5000 watts as this can be a major source of free heat to be put into a thermal store so providing heating and hot water to the property. The charts below give an example of what can be achieved.

A typical specification of a 6 metre turbine.

Parameter	Details
Rotor Diameter	6.0 metres
Rotor Type	3 Blade Downwind
Blade Material	Glass Reinforced Composite
Rated Output	5000watts at 11m/s (24mph)
Peak Output	6000watts
Cut-in Speed	3m/s (6.7mph)
Estimated AEP	7,000-20,000kWh per year Depending on site location and wind
Weight	265kg
Generator Type	3-Phase Brushless NIB Dual Rotor Out-runner PMA
Grid Tie Equipment	SMA WB6000
Control	Flight Computer, Auto Shut-Down, Over Voltage, Mechanical Brake.
Acoustic Levels (at 30m)	53dB(A) - Equivalent to normal speech
Lifetime and Servicing	20 Years Annual Inspection Recommended
Warranty	2 Years

Installing a Small Wind Turbine – Summary

Get a reliable estimate of the wind speed at the proposed site. Turbine manufacturers should be prepared to help. The generator must get acceptance for connection to the electricity distribution network. (if applicable).
Mount the turbine on as high a tower as possible and well clear of obstructions. Easy access will be required for erection, and foundations for the tower may be needed depending on the size and tower type. It is also important to ensure that the wind turbine can be easily lowered for inspection and maintenance.
Try to have a clear, smooth fetch to the prevailing wind, e.g. over open water, smooth ground or on a smooth hill.
Use cable of adequate current carrying capacity (check with the turbine supplier. This is particularly important for low voltage machines). Cable costs can be substantial.
Consult your local council as to whether you need planning permission. You should try to minimise the environmental impact of the turbine, and it will be helpful to inform your neighbours of your plans at an early stage.
Once the machine is under construction, ask your chosen supply company whether they need you to be accredited for ROCs, LECs, & REGOs and what type of onsite and/or export metering they require you to have (if applicable). By changing to a green electricity supplier, you can generate a substantial return on a microgeneration tariff.

Connecting to the National Grid
Both Solar electricity (PV) systems and wind turbines can be connected to the National Grid. Unless you are in a remote property with no access to mains electricity, a deal with the National Grid means you can avoid the use of bulky, expensive batteries to store the electricity you generate. In effect, you treat the National Grid like a great big battery – you put any surplus electricity you generate into the grid when the wind blows or the sun is shining then take back what you need when the weather doesn't allow you to generate enough electricity of your own.