SunPower broke ground this week on a 13.78-megawatt solar photovoltaic power system at the Naval Air Weapons Station China Lake in California.

An affiliate of MetLife, Inc. purchased the system that SunPower designed and is building. The Naval Air Weapons Station will buy the power back at rates below current market rates for power.

The solar installation is the first project on federal property financed with a 20-year power purchase agreement rather that a 10-year agreement, SunPower spokeswoman Ingrid Eckstrom said.

“The 20-year PPA allows the Navy to secure electricity at prices below the utility rate,” Eckstrom said, “and up to 30 percent below the rate available through shorter duration 10-year PPAs.”

She said the 20-year agreements are better aligned to take advantage of the full life of the solar system, which has a 25-year warranty.

“Also, financiers are generally more knowledgeable of and comfortable with longer terms,” Eckstrom said.

While this is the first time a 20-year term has been used in a government contract, Eckstrom said they are standard in the private sector.

The solar project will occupy approximately 118 acres in the southeast portion of the base. It’s expected to generate about 30 percent of the base’s total energy consumption. And the project is expected to employ more than 140 people during construction. It will also save the base over $13 million over the next 20 years, according to a release from SunPower.

“The system size was determined by the dual objectives of maximizing the savings for the base, and complying with requirements of the regional utility,” Eckstrom said.

SunPower has had several contracts with government and military entities and will have more than 25 megawatts of installed solar on federal government land when this project is complete before the end of this year.

It’s only slightly smaller than the 14.2-megawatt solar plant installed at the United States Air Force Academy in Colorado Springs, Colo. That system is featured prominently at the southern entrance to the base. Eckstrom said she didn’t believe this one would be visible to the public.