The first power has been generated from the world’s largest offshore windfarm, the companies behind the scheme said on Monday.

The first phase of the London Array project, around 12 miles off the coasts of Kent and Essex in the Thames Estuary, will see 175 turbines generating enough power to supply more than 470,000 homes.

Already 151 turbines have been installed since construction began in March 2011, and when the first phase is completed by the end of the year, the 630-megawatt scheme will be the largest offshore windfarm in the world, the companies said.

If approved, the second phase will add enough turbines to bring the total capacity of the windfarm to 870MW. The plans have had to be resubmitted with a reduction in the area the turbines would cover following concerns the scheme would hit the red-throated diver population in the estuary.

Dong Energy has a 50% stake in the project, energy giant E.ON owns 30% and Abu Dhabi renewables company Masdar has a 20% stake.

Benj Sykes, wind UK country manager at Dong Energy, said: “Being able to efficiently develop large offshore windfarms and harvest the scale advantages in both construction and operation is an important element in our continuous efforts to bring down the costs of energy of offshore wind.”

Tony Cocker, chief executive of E.ON UK, described the first generation of power as an important milestone not only for London Array but for the global renewables sector.

He said: “We firmly believe that electricity from renewable sources has a vital part to play in helping us deliver energy in a way that is sustainable, affordable and secure and this is why we are aiming to reduce the costs of offshore wind by 40% by 2015.”