Also known as the European Offshore Wind Deployment Center (EOWDC), the site will be used to study new wind power technology and research how marine life is affected by wind farms.
It features 11 massive wind turbines and is expected to provide a total of 312GWh a year, enough power to supply around 80,000 households.
One single rotor lap from one of the record 8.8MW turbines can provide a home with electricity for a full day.
Gunnar Groebler, Head of Business Area Wind at Vattenfall, said: “The fact that EOWDC now can start delivering electricity after a very short construction time is satisfactory.
“Now Vattenfall is given the opportunity to continue to push forward the development of tomorrow’s wind power technology, thus helping our customers to live fossil-free within a generation.”