The wind farm is being redeveloped at a cost of around 11 million pounds
Britain's first commercial windfarm at Delabole in North Cornwall is being re-developed at a cost of around 11 million pounds.
The new turbines will be twice the size of the old ones.
There will be fewer of them but the windfarm will still produce more power than before.
Delabole wind farm came into operation in 1991 and since 2002 has been owned and operated by Good Energy, which is investing £11.8m to re-power it.
The repowering of Delabole will see the ten existing turbines replaced with four modern, more powerful, Enercon turbines to harness the wind resource more effectively.
The four new turbines will be nearly twice as tall standing at 99m
With a total combined capacity of 9.2MW, these turbines will increase the wind farm's output by roughly two and a half times, enough to supply over 7,800 homes.
There are currently 10 50m (164ft) turbines at the site which supply power to about 2,700 homes.
The four new turbines will be nearly twice as tall - standing at 99m (325ft) to the tip of the blade.
Delabole wind farm was built by the Edwards family in 1991 as a greener alternative to plans for a nuclear power station in the area.
Good Energy's founder, Juliet Davenport, said: "Delabole is a fantastic example of home-grown energy.
"Increasing the capacity of Delabole will help contribute to Cornwall's renewable energy targets, increase price stability for our customers and take another step in helping the UK reduce its carbon footprint."
"We are currently working around the clock to re-power Delabole - upgrading to brand new state of the art turbines that will dramatically increase the output of the wind farm so it can supply even more of our customers with clean, renewable electricity".
Goonhilly wind turbine
The current turbines at Goonhilly on the Lizard are nearing the end of their 20-year life cycle.
Originally installed in 1993, they are now to be replaced.