Ethical living

Blowing in the wind

B&Q is now selling wind turbines over the counter. But how easy are they to install? And do they work? Dominic Murphy gives the lowdown
How do they work?

Turbine blades rotate in the wind, turning a copper coil inside a magnetic field and creating an electrical current, in the same way as a dynamo. The Department of Trade and Industry estimates that by 2050, 6% of all our energy could be generated this way, with mini windmills either attached to the home, or to a mast in the garden. There are two basic systems: stand-alone or grid-connected. The first has traditionally been used to power batteries in remote areas. A turbine connected to the grid will need a "grid tie inverter", which converts the current to the 240 AC mains voltage.

How much will it cost?

A typical one-kilowatt domestic turbine will cost upwards of £1,500. With installation, this could rise to £2,500-£3,000. Larger systems in the region of 1.5kW to 6kW come in at between £4,000 and £18,000. Many turbines qualify for a government grant of a third of their cost (0800 915 7722;, and prices are expected to come down as demand increases: B&Q anticipates selling 50,000 of its Windsave system, which might explain the price of £1,498, including survey and installation.

Can you install it yourself?

In theory. However, you will need an electrician to connect it to the mains, and will not get a grant unless you use an accredited installer.

Will they make a noise?

B&Q says the noise on its turbines is 40 decibels: "This is the equivalent sound of two people walking in front of your house talking." A study by Nottingham University found that the StealthGen turbine, the windmill David Cameron is proposing to put on his London home, is quieter at 2-3 decibels above background noise.

Do I have to live in a windy area?

Turbines operate best with constant wind, rather than gusting, which can wear out parts more quickly. Average wind speed in the UK is 5.6m/s, which is a gentle breeze, and many models are designed to work at around 4m/s. You can check the average wind speed in your area here, but such measures are notoriously inaccurate, not taking into account local factors such as surrounding buildings and trees.

How much electricity will it produce?

"Up to 30%" of a household's needs is a common figure bandied about, but it verges on meaningless because it is often based on average wind speed. Not only will the true saving depend on how windy your area is, but how much energy your property uses - according to the Energy Saving Trust (, 0800 512012), a typical home uses between 4,000kWh and 7,000kWh per year. So that is two wildly divergent figures from which to begin your calculations.

Can I sell any surplus electricity back to the national grid?

It is quite possible that you could produce more electricity than you need at certain times - at night, say, or in a gale. In which case some turbines will "export" this power back to the grid. In reality, however, it is actually quite difficult to do. First, you will need to invest in a special meter (about £120), then negotiate a rate with your electricity supplier. This will probably be an insulting few pence per unit of power, as opposed to the 11p or more that they are charging you. Compare this with Germany, where micro-generation incentives include paying householders 30p for every unit of solar electricity they export. Much easier is to sign up with a "green" supplier of electricity such as Good Energy, which will pay you around 5p for every unit of power you generate - special meter or not. Then there are ROC (renewable energy certificate) allowances, which is money you can claim from your electricity supplier for reducing your carbon emissions (this could be around £60 a year, though expect some nightmare paperwork to claim it).

Am I going to get back my investment?

The £1,500 question. Again those average wind speeds figure in some controversial calculations. B&Q reckons its turbines will take seven to eight years to pay for themselves at current electricity prices, but a Sussex University study suggested it could be as much as 28 years for some models.

Will I need planning permission?

This year's Climate Change and Sustainable Energy Act requires local authorities to set targets in micro generation, so you could well find a sympathetic ear at the planning department. However, you will still need permission and policy varies from council to council. Building Control will also need to know about your plans.

Do I need a survey?

Nope, but you would be mad not to have one. You can try to find an "environmental consultant" for some advice, but at the moment the wind turbine industry is a young, unregulated pup, so you could end up none the wiser. You can look up the list of accredited models and installers at

Will it structurally damage my house?

A good reason for getting that survey, and a controversial point. Wind turbines mounted on masts have been around for years and are tried and tested energy producers. Those bolted to homes are not, and many have doubts about their suitability. Alternative energy expert Nick Martins, writing recently in Building for a Future, the green construction magazine, says: "This is not the same thing as fitting a satellite dish on the side of a house. I would guess that the lateral thrust exerted by these turbines on a Victorian chimney stack in a high wind would be more than sufficient to topple it. The same might be true of the gable ends of many older houses."

Would I be better off with some other form of micro-generation?

The bottom line is that wind turbines mounted on homes is relatively untried technology. Solar hot water systems, however, which could cost as little as £3,000 and qualify for a grant, have been with us for years. There are no moving parts, so there is less to go wrong, and you don't need planning permission. Also, achieving 50% of your yearly hot water needs is not unrealistic. The cheapest power-saving option? More insulation, switching off appliances and low-energy light bulbs.

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