Vestas said developer MidAmerican Energy has filed a notice with the Iowa Utilities Board (IUB), highlighting an agreement between the two companies.
The manufacturer is set to supply 1,000 V110-2MW turbines to the project, which is still awaiting approval with the board, Vestas said.
Vestas said it would also "exclusively" supply MidAmerican projects that begin in 2016 and qualify for the production tax credit (PTC) "safe harbour", ensuring the projects qualify for the full amount of support.
In April, the Berkshire Hathaway subsidiary pledged $3.6 billion for the new wind energy cluster in Iowa.
MidAmerican has asked the IUB to approve its request by mid-September so that it can take full advantage of the extended PTC.
Wind XI will result in 85% of MidAmerican's customers' electricity coming from renewables.
The cluster will also put Iowa on track to be the first US state to generate more than 40% of its electricity from wind — far ahead of any other state. Currently, it is the only state to generate more than 30% from wind.