Interconnectors allowed 80% of the power surplus to be shared equally between Germany and Norway, which can store it in hydropower systems for use later. Sweden took the remaining fifth of excess power.

“It shows that a world powered 100% by renewable energy is no fantasy,” said Oliver Joy, a spokesman for trade body the European Wind Energy Association. “Wind energy and renewables can be a solution to decarbonisation – and also security of supply at times of high demand.”