Los Alamos County’s Foxtail Flats solar and storage project breaks ground

Los Alamos County has put a hard number on its next big electricity bet: Foxtail Flats is projected to deliver solar-plus-storage power at an average cost of $74.79 per megawatt-hour, with county planners saying the project could help push the county to 72% carbon-free electricity by 2027. County officials marked the project’s groundbreaking on May 14, turning a long-term power contract into a physical buildout with direct implications for what residents and county facilities pay for power.

Foxtail Flats pairs 170 megawatts of solar generation with an 80-megawatt, 320-megawatt-hour battery-storage system under a long-term power-purchase agreement with the Incorporated County of Los Alamos. The county says the project was approved by Council in February 2024 and is being built by D.E. Shaw Renewable Investments, better known as DESRI. It is located on the Ute Mountain Ute Reservation and private land about 10 miles northwest of Farmington, New Mexico, and will connect to an existing substation at DESRI’s San Juan Solar 1 project, which ties into the retired San Juan Generating Station substation.

For Los Alamos County, the value of the project goes beyond adding solar capacity. County materials say Foxtail Flats is part of the county’s push toward a net carbon-neutral energy supply by 2040, a goal first adopted by the Los Alamos Board of Public Utilities in 2013. The battery system is central to that plan because it lets the county capture electricity during the day and shift it into the evening, when demand is highest and power can be more expensive or harder to secure.

A project presentation prepared for Los Alamos estimated that Foxtail Flats would generate about 350,000 megawatt-hours a year, a scale that could materially reshape the county’s power mix. The same presentation said the combined solar-and-battery arrangement would help raise Los Alamos County’s carbon-free electricity share to 72% in 2027, giving the county a measurable benchmark to track well before its 2040 target.

The project also sits inside a larger regional buildout. DESRI said Foxtail Flats and the separate Four Mile Mesa Solar and Storage project would employ about 600 construction personnel at peak. In July 2024, the National Nuclear Security Administration said it was partnering with Los Alamos County to supply electricity from Foxtail Flats to the Department of Energy’s two New Mexico national laboratories, underscoring how the county’s utility decisions now reach far beyond the mesas around Los Alamos and into the broader energy system that serves the region.