A Chinese wind-turbine company, with financing help from Beijing, has struck a deal to be the exclusive supplier to one of the largest wind-farm developments in the U.S., a sign of how Chinese firms are aggressively capitalizing on America's clean-energy push.

The 36,000-acre development in West Texas would receive $1.5 billion in financing through Export-Import Bank of China. Shenyang Power Group, a five-month-old alliance, would supply the project with 240 of its 2.5-megawatt wind turbines, among the biggest made in the...