Wind farm operators have been paid nearly £360million to switch off turbines because they are producing more power than the grid can take.
These ‘constraint payments’ have soared since 2010 – yet more turbines continue to spring up across the country.
National Grid, the power transmission network, compensates energy providers if it asks them to switch off to prevent the grid becoming overloaded.
A record 69 wind farms were paid to stop transmitting in the last weekend of October.
Analysis of National Grid figures shows it paid £334.7million to wind farms between 2010 and September this year. It is estimated to have paid a further £24.5million since then.
Critics said the rising costs, ultimately passed on to the public, were bad for consumers and showed the industry was ‘seriously overheated’.
Payments have risen from £200,000 in 2010 – the first year they were made – to £85.4million in 2016.
The average price this year was £70 per megawatt hour.
Scottish wind farms are the primary recipients of constraint payments because there are growing numbers of turbines north of the border, encouraged by Holyrood. But a £1billion subsea cable, due to open in 2015, to bring the extra wind power south has been delayed due to manufacturing problems.
Several recent payments have gone to new wind farms, meaning they are asked to switch off almost as soon as they open. The money is not pure profit – power generators will have already paid out to access the transmission system.
Dr Lee Moroney, research director at the Renewable Energy Foundation (REF), said: ‘The fact that new wind farms are constrained off as soon as they start generating, sometimes even before they are officially opened, shows that the Scottish Government has allowed the wind sector to become seriously overheated.
‘This is very bad for consumers, who have to pay high constraint payments in the short run and high grid expansion costs in the longer run.’
Wind farm numbers have ballooned since the 1990s, encouraged by government. But it ended subsidies last April, saying there were now enough projects to meet renewable energy needs.
Despite this, £63million was doled out to switch off turbines between January and August, meaning this year’s bill looks set to be the highest yet.
The total cost to National Grid of switching gas producers on or off since 2014 is £985.4million. In all, it has spent around £1.6billion since 2014 switching different energy sources on or off because the grid cannot cope with all the power they produce, including compensating owners.
Industry body Renewable UK said the figures showed constraint payments for wind should drop to nearly zero once the subsea cable is operating.
A National Grid spokesman said: ‘Wind constraint payments are the most economically efficient way of managing additional green capacity while we retain and reinforce capacity on our electricity network, such as the £1billion Western Link subsea connection that will bring renewable energy from Scotland to the UK.
‘This strategy is delivering, with National Grid announcing that the summer of 2017 was the greenest ever with almost 52 per cent of our electricity generation met by low carbon sources, compared to around 35 per cent four years ago.’