The 8.22-megawatt SunEdison plant, with its photovoltaic arrays on 82 acres, produced enough power for 1,652 homes, making it the largest plant of its kind in the country.

The Alamosa plant might not be the biggest for long. Construction was recently completed on a 10-megawatt photovoltaic plant in southern Nevada that will serve customers of Pacific Gas and Electric Co.

"Not to pooh-pooh Alamosa's size, but the industry is growing fast," said Mike Taylor, director of research for the Washington, D.C.-based Solar Electric Power Association.

"I'd almost call it entry-level," Taylor said. "But you've got to start somewhere. So kudos to the Colorado initiatives that got them out in front on this project."

Xcel Energy is using the plant's power to help it meet the renewable-energy standards approved by Colorado voters and the Legislature. A law passed this year requires utilities to derive 20 percent of their power from renewable energy sources by 2020.

"We have been very pleased with the amount of solar power the SunEdison plant has been able to deliver," said Karen Hyde, vice president of resource planning and acquisition for Xcel. "We continue to believe that solar power will be an integral part of our resource strategy."

Xcel customers pay about 2 percent more on their power bills to finance renewable energy, mostly from wind.

Experts say the station's successful first year should help convince utilities that sun power can be a viable part of the energy mix even though the costs are higher and the output more variable than conventional coal- and natural-gas-fired generators.