Unsubstantiated Claims of Rooftop Wind Turbines

By Hugh Piggott

5 Jan 2007

The following is an open letter by Hugh Piggot to BWEA calling for action on the unsubstantiated claims by promoters of rooftop wind turbines in Britain. Hugh Piggott is one of the world’s most knowledgeable authorities on small wind turbines. You can see reviews of his books elsewhere on this website.

CEO, British wind Energy Association

Dear Maria McCaffery,

I am writing to you because I am very concerned about the claims made by Windsave and other rooftop wind turbine manufacturers and their agents. I suggest that BWEA would do well to distance itself from these people before the resulting fiasco reflects on the windpower industry as a whole.

For example, last night on TV I saw the boss of B&Q confidently assert that a Windsave turbine would save a typical householder 25-40% of their electricity bill. I was very pleased when the interviewer did ask if there was enough wind. This is a big worry for me. I know there is not enough wind in most city locations to make this possible. He replied that maybe 20% of sites would not be suitable. I don’t think he has a clue what he is getting into.

There does not appear to have been any systematic assessment of the wind resource at rooftop level in an urban environment. This seems ludicrous given that Windsave attracts a 30% grant from LCBP. My own tests over one year in Edinburgh revealed a huge shortfall of wind compared to the annual mean that might be expected based on NOABL. The Windsave web site (which is full of glaring errors) states that “According to the Department of Trade and Industry (DTI), the average wind speed across the UK is approximately 5.6 metres per second [m/s] at 10m above ground level (agl).” This nonsense is widely believed. Of course it is not true because of localised obstacles, especially in built-up areas where the turbines will be sold.

My experience is that the general public have highly inflated expectations of small wind turbines. I have been in the business for nearly 30 years and I am constantly dealing with people who wildly overestimate the amount of energy they will get from small wind turbines. I spend much of my time educating them and explaining that windpower will not do what they expect. There is a massive opportunity for marketing here, but only for the unscrupulous (or ignorant). I am very surprised that BWEA are willing to even recognise organisations such as Windsave and Renewable Devices Swift Turbines that make wild claims for their rooftop products. This can only end in tears. There are very few sites where the expected energy can be produced. Siting a wind turbine below the ridge of a building (at bedroom window level) in the back garden of an urban dwelling as shown in the product literature is absolutely crazy!

I strongly suggest that BWEA make some sort of public statement warning of the dangers of this latest marketing racket. Otherwise wind energy as a whole will take a massive hit to its credibility. I suggest that you demand evidence from Windsave and RES to support their improbably energy production claims. I suggest that you contact the BRE and the EST and get them to do their homework before they offer grants for these installations.

What I find is that when people learn that small wind turbines cannot deliver on their assumptions, they go on to assume the wind energy as a whole is a waste of time, or worse a complete scam. We need to educate the public to understand what wind energy can do and what it cannot. My experience is that when people learn how little energy is available at rooftop level, they immediately extrapolate this lesson to windfarm level, and decide that wind energy is completely irrelevant (see for example http://www.timhunkin.com/a125_arch-windpower.htm).

I really hope that you will take this request seriously. If nothing else, please try to find out more about the wind at rooftop level in the UK. I think you will find that there is not enough to do anything useful. This is a matter of some urgency now, and soon it will be too late to avoid a complete disaster for the industry.

All the best, and let’s hope for a windy new year

Hugh Piggott
Scoraig Wind Electric
Ross shire
IV23 2RE
01854 633 286
01854 633 233 (fax)
+44 1854 633 286 (international)
+44 1854 633 233 (international fax)

For more on rooftop wind turbines and other questionable practices see Inventions & Questionable Wind Turbines.