The turbines are destined for the Los Vientos II project in Texas. It comes alongside a second 200MW deal for the Los Vientos I project, which has gone to Siemens.
However, Duke’s decision to go with the MHI’s 2.4MW turbine is likely to spark the most discussion.
It is the first major US order since the Japanese company became embroiled in a patent dispute with GE.
GE claim the MHI2.4 infringes numerous patents including the turbines low-voltage-ride-through technology.
Last year, a lawyer representing MHI claimed the case was "shutting down sales" of the turbine by creating uncertainty for developers seeking financing.
Speaking at the Federal court lawyer Filiberto Agusti said: "We are effectively shut down (without financing)," Agusti told the court. "A lot of people are watching this case."
Agusti also reiterated a claim made by MHI in the Japanese company’s anti-trust complaint: that MHI has gone from $2 billion in annual US sales of its 2.4MW turbine to almost zero because of GE’s suits against MHI alleging infringement of five patents.