From the Sunday Times (not online; via commenters)
Wind farm operators in Scotland were paid nearly £900,000 to keep their turbines idle for a night because the National Grid did not need the power.
The payments, up to 20 times the value of the power the wind farms would have produced, were offered by the National Grid because it urgently needed to reduce electricity entering the system.
It was oversupplied with power on a wet and blustery night last month when demand for electricity was low.The National Grid confirmed it had made the payments. “On the night of April 5 and 6, the demand for power was low but the nuclear generation plants in Scotland were running as expected. There was also heavy rainfall, which meant hydro power plants were operating well, too,” a spokesman said.