“It was like a bomb hitting the roof of the house. It shattered the tiles and the blade disintegrated itself,” David Campbell told the Belfast Telegraph.

The turbine was one of a batch of 11 defective machines installed on farms in Northern Ireland with the help of European funding provided by the Department of Agriculture.

All 11 of the Chinese-built turbines, sourced from the same supplier, have broken down but the farmers have been left thousands of pounds out of pocket and they complain that no-one is doing anything to help.

Mr Campbell said the turbines, supplied by Co Tyrone company Adman Building & Civil Engineering, were only operating for a matter of hours before they broke down. He said his turbine “took off of its own accord” one stormy night in January 2007: “It got up momentum with the wind blowing. It went for four hours until about 4am and the three blades came off. One of the blades went through the roof of the house — it cut through it like a chainsaw.

“If anybody had been in line of them when they came off, they definitely would have been killed — the blades are 16 foot long.”

Gavin Hayes, who installed another of the turbines in 2006 grant-aided under DARD’s Building Sustainable Prosperity programme, said a total of 30 wind turbines were erected across Northern Ireland, of which 11 were the defective type.

He said the farmers had trusted DARD which had approved two suppliers.

The scheme cost farmers £45,500, but they were able to claim a £15,000 grant from DARD and £5,000 off the Carbon Trust.

Two turbines shed their blades while operating, two took off on their own and shed their blades and the other seven have lain unused since they were installed, he said. The turbine at Mr Hayes’s house shed its blades; one smashed the poultry house roof.

“All you are left with is a 25-metre flag pole which is not fit for purpose. We thought the WREAN men had done their research. We went into the scheme on the back of DARD thinking all the research had been done.”

The farmers are now stuck with a monthly payment of around £400 over a period of eight years.

A DARD spokesperson said the Wind Energy For Rural Businesses project was funded under the EU programme for Building Sustainable Prosperity, which ran from 2001 to 2006. He added:

“Whilst the Department do not have any direct responsibility we continue to monitor the situation and have been in contact with the promoters and their representatives.

“The Department understands the problem arose from a manufacturers fault, and that the supplier and manufacturer is working to resolve the problem. Whilst this work is ongoing the Department cannot become involved in what is essentially a contractual and warranty matter that has potential litigation implications.”