U.S. Energy Secretary Steven Chu announced the loan for Aqua Caliente Solar to support the construction of a solar generating facility in Yuma County, Ariz.
The Energy Department said that when the facility is completed, it would be one of the largest plants of its kind in the world.
"The Agua Caliente Solar project will bring hundreds of jobs to Arizona, while helping increase the reliability of renewable solar power," Chu said in a statement.
The Energy Department said the United States had a dominant position in the solar energy sector in 1995, manufacturing 43 percent of the world's solar panels. That market share slipped to 7 percent last year, however.
The so-called SunShot program by the U.S. government aims to spur American innovations to reduce the cost of solar energy.
U.S. President Barack Obama in a January address to the nation laid out a clean-energy target of meeting 80 percent of U.S. energy needs with clean sources by 2035.