With that capacity, Tasmania has reached its goal of generating 100 per cent of its energy needs from renewable sources.

State government energy minister Guy Barnett said the achievement came on Friday as 29 of the 31 Granville Harbour Wind Farm turbines came online.

"Today is a momentous day, it is an historic day for tasmania, australia and in fact it is globally significant," Mr Barnett said.

"I can feel that electricity moving through my veins it is so exciting to know we are at 100 per cent."

The state government had committed to achieving its 100 per cent renewable energy target by 2022.

Mr Barnett said the figure meant that across any single year, renewable energy was creating at least the state's average annual electricity demand of 10,500 gigawatt hours.

With the 29 Granville Harbour turbines switched on, Mr Barnett said renewable energy was creating in excess of 10,700 gigawatt hours.

This "milestone", Mr Barnett said, would allow Tasmania to further progress other renewable energy projects such as the Marinus Link and plans for hydrogen power generation, as well as put "downward pressure" on household electricity prices.

He said by further pursuing renewable energy projects, the government intended to reach a target of being 200 per cent renewable by 2040.

Mr Barnett made the announcement at the Granville Harbour Wind Farm at the end of a nearly four-year construction, and 17 years after the idea was initially floated on the site.

Project director Lyndon Frearson said the $280 million project had been incredible, to be involved with, but one that came with significant challenges.

"The challenge was that last year we went through one of the wettest winters the West Coast has ever had, just metres and metres of rain," Mr Frearson said.

"All of that rainfall and massive earthworks.

"How do you build that when you're digging big holes in and they're filling up with water.

"It was a real challenge."

The two-and-a-half year construction timeline involved erecting 31 wind turbine towers which rise 136m out of the ground, with a maximum wing height of nearly 200m, standing on a foundation of 700 cubic metres of concrete and 70 tonnes of steel.

"And in the middle of that, Royce is trying to maintain an organic beef property," Mr Frearson said.

Royce Smith is the owner of the Granville Farm on which the wind farm has been built, and on which over a thousand head of prime organic beef are farmed.

Mr Smith said it had been 17 years since someone first approached his family to build a wind farm on the property, and nine years since he and business partner Alex Simpson had given it the go ahead.

"It's been an amazing journey. Standing here today and seeing them all spinning at full pace it is great," Mr Smith approached.

He said maintaining an organic certification throughout the build meant ensuring the farm's "green image" persisted.

"We have had to redesign the farm around the wind farm, but that's the fun bit."

Six permanent staff will operate the wind farm over its contracted 25-year lifespan.