Because of the boom of renewable energy, more and more wind turbines have to be switched off. The reason is power overloading. The network operators must turn down electricity generated from windmills when their power threatens to clog the network. Originally, this was intended only as an emergency measure. The operators of wind and solar parks, however, are being subsidised for electricity that is not produced.
For the grid operator Tennet alone, these costs added EUR 329 million in 2015 – two and a half times as much as in the previous year. The other network operators 50Hertz, Amprion and EnBW had a combined cost of 150 million euros, according to a survey of Wirtschaftswoche among the four network operators in Germany.