The 16.4-megawatt solar farm, built under a 25-year power purchase agreement, was a joint effort between the Air Force Civil Engineer Center, Davis-Monthan AFB, SunEdison, LLC and Tucson Electric Power (TEP).
The array is exceeding expectations.
"We expected the array to provide 35 percent of our total power needs," said Lt. Col. Brian Stumpe, the 355th Civil Engineer Squadron commander. "However, our calculations show it is providing well over 40 percent of our total need, and over 100 percent of our daytime energy usage. This amounts to a $500,000 per year savings for Davis-Monthan and the Air Force."
In its first 10 months, the array produced 33,083,404 kilowatt-hours of electricity, enough to power over 3,600 homes. The base, before constructing the array, paid 8.6 cents per kwh for electricity. Under the power purchase agreement, the rate for the power supplied from the solar array is 4.5 cents per kwh, with an annual increase of 1.5 percent.
"We are very pleased with the performance of the Davis-Monthan array," said Frederick Cade, the renewable energy program manager at AFCEC. "Projects like this go a long way toward meeting Air Force energy goals, and can serve as a model for other installations."
Renewable energy projects like the Davis-Monthan array are part of the Air Force's overall strategy to provide energy resiliency, reliability and security, as well as cost savings. Power systems located on secure installations deliver necessary predictability, and dollar savings free up resources that can be reallocated to other mission priorities.
"For a minimal investment in manpower, projects like this provide substantial savings," Stumpe said. "Since we don't own the project, our civil engineers are freed up to focus on the core mission of operating and sustaining the air base and generating air power."
The Davis-Monthan array also benefits the base's local utility, TEP, said Timothy Davis, the senior director of customer solutions and business development at TEP.
"The Arizona Corporation Commission has implemented the Renewable Energy Standard that requires utilities to increase their production of renewable energy," Davis said. "TEP had a goal of four percent. The Davis-Monthan array has helped us exceed that goal."
The Air Force continues to expand its renewable energy program. Currently, two solar arrays are in the works, a 19-megawatt expansion of an existing 14.7-megawatt array under construction at Nellis AFB, Nevada, and a 20-megawatt solar farm in the proposal phase at Vandenberg AFB, California. Each are larger than the Davis-Monthan array.
"The Air Force has a goal that every base will implement some sort of renewable energy generation," Stumpe said. "This array has exceeded our goal by 36 percent, which contributes to overall Air Force energy savings. We're proud of our work here."