Two vital projects on a remote Hebridean island could be undermined because its community wind turbine lost around £150,000 in revenue in the first three months of this year due to failed grid connections.

The wind was turning the blades of Tiree's turbine, christened Tilley, but the electricity it was generating could not go on to the grid to earn money, due to damage to Scottish and Southern Energy's (SSE) cable to the ­mainland. The island's diesel backup generator had swung into action to ensure the lights were still on in the island's homes.

But the best three months for wind generation had been lost to the Tiree Community Development Trust, which operates the turbine through its trading subsidiary, Tiree Renewable Energy Ltd.

Andy Wright, the trust's finance and governance manager, said: "We effectively lost one-third of our annual turnover from January 1 to March 31. Since the beginning of 2011 the Tiree-Coll section of the sub-sea cable which connects us to the mainland has failed or broken three times. This has resulted in Tiree being cut off from the mainland grid network for a total of eight months during this period."

Under the terms of the deal with SSE, the energy giant is not liable for failure in the cable, so the trust has had to claim on its insurance for loss of revenue.

But the islanders have been warned by their insurance broker that, due to the number of claims, they are "perilously close to being declared uninsurable." As matters stand their insurer will only pay out after the turbine has failed to earn for three months.

Mr Wright continued: "Tiree Renewable Energy has a strict policy on reserves for maintenance and overheads, which means that the turbine operation is not in immediate danger. However the loss has been significant this year."

He said progress on two key projects was likely to be more difficult. "We want to open a community shop to fill the gap left when our last independent food store closed," he said.

There are also plans to look at community ownership of some or all of the island and its assets.

"The money we have lost could have had a huge impact on both projects and on the people of Tiree," Mr Wright added.

The trust and the island's energy company have jointly written to Rural Affairs Secretary Richard Lochhead. A Scottish Government spokeswoman said it was aware of their concerns and would be responding shortly.

A spokeswoman for SSE said: "We have now replaced the whole cable with a heavier-duty one, which was quite a job.

"As far as the security of supply to Tiree keeping the lights on, nobody would have noticed much difference because of the power-station generators."