Crystal Rig's capacity climbed from 138 MW up to 200 MW on 8 September, which – along with the commissioning today of the world's largest operating offshore farm – helped the UK add its fifth gigawatt of installed wind capacity in less than 12 months, said the trade body.

The acceleration in capacity growth to hit the 5 GW target was welcomed by RenewableUK's CEO Maria McCaffery.

"Renewable energy generally and wind energy in particular is not alternative energy any longer - it is absolutely mainstream," she said.

In addition to its 5 GW in operation, the UK has nearly 18 GW of wind capacity either consented, in construction or in the planning system, according to RenewableUK.

With the UK's portion of electricity from renewables now close to 10%, up from about 2% back in 2002, the government's targets for hitting its 2020 goals are "realistic and achievable", said McCaffery.

Wind in the UK now provides enough electricity for almost 3 million homes, said the organisation.

Thanet Offshore Wind Farm is a Vattenfall project while Crystal Rig and its extension, Crystal Rig II, was developed by Fred. Olsen Renewables.