SunEdison and its subsidiary, TerraForm Power Inc, have made an agreement to purchase US wind company, First Wind Holdings Inc, for $2.4 billion – making SunEdison the world’s largest renewable energy developer.

The deal is expected to close in the first quarter of 2015. It includes an upfront payment of $1.9 billion and a further $510 million on the completion of backlog wind projects. TerraForm Power is a Yieldco, which is a publicly traded company formed to own operating assets that produce a predictable cash flow. As such, they will take over First Wind’s operating portfolio of around 510MW’s worth around $862 million.

“Wind is a great asset class and we see tremendous growth potential. For us this is a logical expansion into renewables,” says TerraForm Chief Executive Officer Carlos Domenech.

Also included in the deal is around 1.6GW’s of pipeline and backlog projects that should be operational in 2016 / 17 (to be handed down to TerraForm Power) and 6.4GW’s of development opportunities. TerraForm is expected to add 4.6GW’s of capacity, wind and solar, to its portfolio by the end of 2017.

“The acquisition of First Wind transforms both SunEdison and TerraForm Power into diversified renewable energy companies and will make SunEdison the leading renewable power plant developer in the world,” said Ahmad Chatila, President and Chief Executive Officer of SunEdison.

“We are excited to become part of the SunEdison team,” said Paul Gaynor, Chief Executive Officer of First Wind. “This new strategic organization will allow us to join with SunEdison to develop and invest in new, long-term-contracted, well-sited and well-run renewable energy projects that deliver clean energy to homes and businesses across the country and internationally.”