Britain's windfarms broke a new record on Friday by providing over four gigawatts of power to the National Grid – enough to light and heat more than 3m British homes.

It beats a previous high of 3.8GW set in May and comes as a further 4GW of wind turbines are being installed, half on land and half offshore.

Just before 10am, wind turbines were supplying 10.8% of the total amount of electricity going into the grid while an additional 2.2GW of "green" power was going directly into local electricity networks.

"This record high shows that wind energy is providing a reliable, secure supply of clean electricity to an ever-greater number of British homes and businesses," said Maria McCaffery, chief executive at the campaign group RenewableUK. "As our wind energy capacity increases, the need to import expensive fossil fuels starts to diminish. The transition to a low-carbon economy is well under way and harnessing this bountiful, free resource will help us to drive down energy bills for all users in the long term."

Critics will point out that the 4.1GW total compares with the UK's largest coal and biomass-fired power station, Drax in North Yorkshire, which produces almost that amount of power on its own.