Except when they turn the wind turbines off, we the bill payers have to pay them a constraint payment amounting to millions of pounds a year. The pump generating stations like Dinorwig were built to smooth out demand not supply. They would buy in power. for pennies a kilowatt at night and sell it back to the grid for pounds when the likes of Eastenders finished and everyone put the kettle on, causing a surge in the grid. The operators in the control room would have a copy of the TV and Radio Times and a telly with the sound off so that they would know when to open the penstocks to compensate the grid. With todays chaos on the grid caused by renewals they must be making a fortune out of us.