The scale of the payments has ballooned in the past two years. In 2012, wind farms were paid £5.9 million to switch off. In 2014, those payments – known as constraint payments – had increased 10-fold to just over £53 million, according to the think-tank Renewable Energy Foundation (REF), which compiled the figures using official data. The true figure is likely to be much higher because not all payments are made public.