More than half of the turbines installed at the 567MW wind farm off the North Wales coast have been commissioned and are generating electricity.
Operator RWE Innogy UK said the 81st turbine in the Gwynt y Mor wind farm was connected to the National Grid last week.
The £2 billion project is set to become the second largest offshore wind farm in the world after the London Array in the Thames Estuary.
A total of 160 turbines have been installed at the site so far but all the turbines are expected to be commissioned by the end of the year.
Energy Minister Matt Hancock said: “This is a positive step forward for the industry and shows that investing in offshore wind pays off. Home-grown energy sources will strengthen our energy security, reduce carbon emissions and protect us from volatility in energy markets abroad.”