The €1.3bn ($1.62bn) wind farm, some 23km off the island of Heligoland with 80 Siemens 3.6MW turbines, was built in 18 months.
That was despite having suffered grid-connection delays and facing a costly clearance of unexploded World War 2 debris at the bottom of the sea.
"The inauguration today of the Meerwind Süd/Ost offshore wind park is a strong signal that the Energiewende is advancing successfully in Germany," said Uwe Beckmeyer, secretary of state at the economics and energy ministry.
