Building work on the Coonooer Bridge Wind Farm near Bendigo is set to start today.

It was one of three wind farms in Victoria and South Australia to win 20-year deals with the ACT government to supply a third of Canberra's electricity needs within two years.

The deals are worth a total of $68 million a year to the three companies and will cost Canberra households an average $93 extra a year on their power bills at the peak in 2020.

The farm will help the ACT meet its goal to source 90 per cent of Canberra's electricity from renewable energy by 2020.

Environment Minister Simon Corbell said the Victorian farm would generate "the lowest-cost wind energy in Australia" at $81.50 per megawatt hour.

"Wind is currently the lowest-cost renewable energy generation available, and will play a big role in the decarbonisation of the ACTs electricity supply.

"It will contribute approximately three-quarters of the ACT's 90 per cent renewable energy target."

Mr Corbell said an expected annual output of 82,000 megawatt-hours would be enough to power about 12,000 homes.

The farm will be managed by wind energy development company Windlab from its global operation centre in Canberra.

The hub was set up as part of the company's bid for the wind auction and currently employs 15 staff, a number which should grow to 70 by 2035.

Construction of the Coonooer Bridge Wind Farm should be finished in the first half of next year.