The names and locations of the wind farms have not been revealed. Vestas' manufacturing facilities in the US will produce the blades, nacelles and towers for the projects.
Susan Reilly, chief executive of RES Americas, said: "This is a great example of how the 'start-of-construction' language in the current production tax credit for wind energy is generating increased spending and creating US manufacturing jobs.
"This purchase, which we expect to increase as these projects move forward, would not have occurred but for the decision Congress made to qualify any project that starts this year."