ScottishPower hopes to have a total of 140 turbines constructed by summer 2009, which would take the operational power of the windfarm to 322 megawatts of electricity.
Keith Anderson, director of ScottishPower renewables, said the firm's commitment at the site will "strengthen investor confidence in the UK renewable industry".
He added: "It is fitting that Scotland - a country that has some of the best renewable resources in the world - is home to most powerful windfarm in Europe.
"It is an achievement we can all be proud of."
ScottishPower recently announced it will have installed energy efficient measures in over 380,000 homes by the end of 2008.
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