Coming soon: The biggest solar farm east of the Rocky Mountains by Katie Fehrenbacher @FortuneMagazine August 20, 2015, 12:59 PM EDT E-mail Tweet Facebook Linkedin Share icons Most of the really large, sprawling solar farms have been built in the Southwest of the U.S., in sun-soaked states like California, Nevada, and Arizona. But this week clean power company SunEdison broke ground on, and secured financing for, the biggest solar farm in the U.S. east of the Rocky Mountains, just south of Pueblo, Colorado. When completed next summer, the “Comanche Solar project” will use at least 450,000 panels across 900 acres of land, and deliver 156 megawatts of energy, which is enough power for 30,000 Colorado homes. Public Service Company of Colorado, subsidiary of power giant Xcel Energy, will buy the power from the farm over 25 years. SunEdison expects to spend $253 million on the project, which it acquired from developer Community Energy last year. SunEdison is working with Renewable Energy Systems America on the construction. So why Colorado? Xcel Energy has had a plan to generate 170 megawatts of energy from large utility-scale solar farms in the state and the 156 megawatt Comanche project will deliver the bulk of that. Colorado has a mandate that says utilities must deliver 30% of their energy from renewables by 2020. The state was the first to enact the law—commonly called a Renewable Portfolio Standard, or RPS—through a ballot initiative. While 156 megawatts is large, it’s not close to the really huge mega solar farms that have been built in California in recent years. California is home to the largest solar panel farms in the world, including the 550 megawatt Topaz Solar farm, near San Luis Obispo, the 550 Desert Sunlight project in the Sonoran Desert east of Joshua Tree, and the 579 megawatt Solar Star, made of two co-located projects in Rosamund, Calif. However, these super huge solar farms likely don’t represent the future of U.S. solar growth. Smaller solar panel farms—closer in size to the Colorado project—will make up the majority of new utility-scale solar projects. That’s because the really huge solar farms can take many years to get built, and often face push back from environmentalists about sensitive lands and habitats for endangered animals. Much of the future growth in solar panels in the U.S. will also come from installing them on rooftops for home-owners and businesses. In the first quarter of this year, there was more energy from residential solar panels installed than energy from natural gas power plants built. Three million new home rooftop solar installations could be built in the U.S. over the next five years, a number that would dwarf even the biggest solar farm. Subscribe to Data Sheet, Fortune’s daily newsletter on the business of technology.