Some of the 300,000 computer-controlled, garage-door-sized mirrors at the facility — owned in part by Google — reflect sunlight to boilers that sit on 459-foot towers. The sun heats water in the boilers' tubes making steam, which drives turbines to create electricity. Chris Carlson/AP

A solar plant in the Mojave Desert — the largest of its kind in the world — officially opened Thursday, and began providing energy to customers in California.

The opening is seen as a milestone for a growing industry that is testing the balance between wilderness conservation and the pursuit of green energy across the American West.

The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, formally opened Thursday after years of regulatory and legal tangles ranging from relocating protected tortoises to assessing the impact on Mojave milkweed and other plants.

"The Ivanpah project is a shining example of how America is becoming a world leader in solar energy," U.S. Energy Secretary Ernest Moniz said in a statement after attending a dedication ceremony at the site. "This project shows that building a clean-energy economy creates jobs, curbs greenhouse gas emissions and fosters American innovation."

The $2.2 billion complex of three generating units, owned by NRG Energy Inc., Google Inc. and BrightSource Energy, can produce nearly 400 megawatts — enough power for 140,000 homes. It began making electricity last year.

While solar power accounts for less than 1 percent of the nation's power output, thousands of projects from large, utility-scale plants to small production sites are under construction or being planned, particularly across the sun-drenched Southwest.

The plant's dedication comes as government continues to push for development of greener, cleaner power. According to U.S. Energy Information Administration data, the cost of building and operating a new solar thermal power plant over its lifetime is greater than generating natural gas, coal or nuclear power.

But that could be changing soon. Ken Johnson, a spokesman for the solar association, said in a statement that solar systems have seen "dramatic price declines" in the last few years.

Comparing the production costs of solar energy versus coal, oil and gas, or nuclear ignores costs resulting from environmental pollution and accidents from traditional energy sources, environmentalists say. Taking this into account could make solar a "cheaper" option.