Lincoln said the new owners would allow up to $250 million to be invested into renewables by 2018.
Lincoln has developed more than $1.5 billion of clean energy projects, totalling 1GW across North America, according to the asset firm.
I Squared Capital said the recent extension of the production tax credit for wind and investment tax credit for solar make the US an attractive investment.
"This is an opportune time to invest in the renewable energy sector, and we are delighted to partner with Lincoln's high-calibre management team, with its proven track record in the development and management of clean energy projects.
"Lincoln's operational experience and track record, combined with I Squared Capital funding and expertise, positions Lincoln to become a premier renewables generation company in the US," said I Squared Capital Partner, Adil Rahmathulla.
Lincoln's wind portfolio includes the 200MW Heredord and 300MW Jumbo Road wind projects in Texas. Both were sold to "strategic owners" during the construction phase.