In a major step for the only Island-based partnership in the race to develop offshore wind, Vineyard Wind won the right to negotiate a 20-year state contract today to build an 800-megawatt wind farm south of Martha’s Vineyard.

One of three bidders for the state-mandated energy contract, Vineyard Wind will now move on to the next step in the process: negotiating a contract with the state Department of Public Utilities.

“It was the best project,” Massachusetts Secretary of Energy and Environmental Affairs Matt Beaton said, speaking to the Gazette by telephone Wednesday.

Three developers have been awarded leases to build wind farms in federal waters 12 nautical miles south of the Vineyard. All three were in the running for the state energy contracts.

Tied to a 2016 law signed by Gov. Charlie Baker requiring utility companies to buy 1,600 megawatts of power from alternative energy sources in the next decade, the contracts are critical since they provide a way for wind farms to transmit electricity to consumers via the grid.

Vineyard Wind is a partnership between Avangrid Renewables and the Danish company Copenhagen Infrastructure Partners.

Secretary Beaton said the Vineyard Wind project wound up being ranked number one in a complicated evaluation process, partly because of its stated commitment to community benefits, including workforce training.

“A lot of folks on the Vineyard are well aware of the Vineyard Wind team creating their new home on the Vineyard, their commitment to wanting to make sure this first, largest-in-the-nation offshore wind development not only delivers in a cost effective way, but in a socially and environmentally responsible way . . . that really took it to the head of the crowd,” he said.

The bid was also the lowest, said Judith Judson, Massachusetts Department of Energy commissioner, although the amount will not be disclosed until negotiations begin with the state Department of Public Utilities.

She said the Vineyard Wind bid was best positioned to take advantage of federal tax credits, which are declining and expected to be phased out in the near future.

Secretary Beaton said the bids were evaluated by a team that included state utility companies Eversource and National Grid. “It was an incredibly robust process,” he said.

He concluded: “This puts Martha’s Vineyard back in the spotlight for all the reasons we know — it is a place that is environmentally conscious . . . and now it has the potential to lead the way in creating clean energy for all of Massachusetts through offshore wind farms.”