The Interior Department says approval was granted last week for the Soda Mountain Solar Project.
The 287-megawatt plant would be built six miles southwest of Baker near Interstate 15, the highway that links Southern California and Las Vegas.
The Center for Biological Diversity said it opposes the approval, arguing the plant would block a travel route for bighorn sheep and impact the neighboring Mojave National Preserve.
The Interior Department says it approved a revised plan that dealt with those issues.
The plant has another hurdle: nobody's agreed to buy its electricity. Los Angeles dropped purchase plans last year, saying there were cheaper sources.