Prime Minister David Cameron said world's largest offshore wind farm was ''good for Kent and good for Britain.''
Mr Cameron described London Array, in the outer Thames Estuary, as a "big win for Britain" which proves the country is capable of delivering large-scale projects.
A small group of protestors shouted slogans as Mr Cameron's car drove in and out - and demonstrated against government cuts.
The PM was speaking at Turner Contemporary in Margate at the inauguration of the fully functioning wind farm, which reached full capacity earlier this year with the commissioning of its 175th and final turbine.
Mr Cameron said the project represented a huge investment for renewable energy and was providing jobs for local people. He denied that mainly overseas companies were benefitting from the construction.