Companies with wind farms in Scotland received more than £5 million earlier this month.

The money, which covers a 12-month period, was paid out because the National Grid cannot handle the extra energy that Scottish wind turbines produce during stormy weather.

The so-called ‘constraint payments’ are paid by consumers through a subsidy that is added to their electricity bills.

Scotland hosts more than half the UK’s onshore turbines, but demand is insufficient to use much of the power produced on windy days, and cable networks to take the power south of the Border are not yet ready.

National Grid has to pay the wind-farm owners to stop generating in order to keep supply and demand balanced.

Critics said that the figures undermine claims made by the Scottish Executive government that wind energy can help Scotland achieve its target of producing 100% of its energy from ‘green’ sources by 2020.

Although energy policy is dictated by Westminster, the SNP has used its control over the planning system to encourage the construction of thousands of turbines.

Scottish Conservative energy spokesman Murdo Fraser said: “This is an incredible financial bonus for a form of energy that is unreliable and intermittent. Taxpayers will be appalled at this spend, particularly as a reward for effectively doing nothing.

“It shows why the UK Government was quite right to end the subsidy for wind farms and put the brakes on this ‘gravy train’ before it gets out of hand.” Lee Moroney, research director of the Renewable Energy Foundation (REF) agreed: “Paying wind farms not to generate has always seemed outrageous, and it is going up each year.”

However, Michael Rieley, senior policy manager at Scottish Renewables (www.scottishrenewables.com), said: “Constraint payments are not new, nor are they restricted to wind farms. National Grid pays a variety of technologies to reduce or increase their output — as required — to balance the system. These payments are a normal part of the overall efficient management of our electricity system, given the limitations of the UK’s ageing energy infrastructure.”

The Scottish Executive government said that National Grid figures show gas power stations have received constraint payments worth £101.4 million over the last year.