The five operating wind farms in Idaho and Oklahoma can generate about 521MW of energy and include contracts to sell their output to utilities with an average life of 18 years.
Atlantic Power president and chief executive officer James Moore said: "This transaction represents a compelling valuation for our assets and will enhance our financial strength and flexibility."
The transaction, which is subject to regulatory approvals, is expected to be completed in the second quarter of 2015.
TerraForm expects the plants will generate adjusted earnings before interest, taxes, depreciation and amortization of $56m a year on average during the next decade. The company will also assume debt from the plants.
The company has secured fully committed bridge financing of about $515m to support the transaction.
TerraForm plans to fund the acquisition with a drop down warehouse facility in partnership with third party equity investors and its sponsor SunEdison.
The five projects increases the TerraForm Call Right projects list to 4GW from 3.4GW.
TerraForm Power chief executive officer Carlos Domenech said: "We expect the warehouse facility to be an innovative financing structure that provides repeatable and scalable funding to secure future growth; we expect the drop down returns to be at parity with the acquisition yields."
Atlantic Power was advised by Goldman Sachs on the transaction and Morgan Stanley advised TerraForm Power.
Image: The five operating wind farms in Idaho and Oklahoma can generate about 521MW of energy. Photo: Courtesy of pakorn/FreeDigitalPhotos.net.
