Fifty-seven thousand solar panels capable of generating 16.4 megawatts of direct current renewable power have been installed at Davis-Monthan AFB in Tucson, Ariz., in what’s being called the world’s largest U.S. military solar project.
The project, known as the Renewable Energy Power Purchase (REPP) agreement for Solar PV Array, was financed, designed, and installed by Sun Edison, which also monitors and maintains the array. A total of 170 acres at the base are covered with the solar panels and their associated equipment — 50 acres at the Chevron area and 120 acres at the West Airfield.
Through the REPP, the U.S. Air Force was not responsible for providing any capital costs for the project. Davis-Monthan AFB provides the land for the array in the form of a 25-year lease and purchases the power generated by the photovoltaic array.
Construction of the array finished in December 2013, and the array began producing power in January.
“On a normal workday this spring, March 24, the entire base was powered off the solar array,” says Greg Noble, Davis-Monthan energy manager. “The array produces 31.4 million kilowatt hours of electricity annually, which is enough to power about 3,000 homes. That’s enough to meet about 35 percent of the base’s annual electricity requirements.”
Noble points out the 57,000 solar panels use a single axis tracker system that tracks the sun across the sky in 15-minute increments. At night, the panels store flat facing the sky, then rotate in the morning to maximize the output of the sun.
Davis-Monthan still gets a monthly electric bill from Tucson Electric Power Corp., the area electric utility, but Noble notes “it is significantly reduced based on the particular month.” The Air Force base also gets a second bill from Sun Edison for the monthly power it uses from the solar array.
Noble says there is a big difference in the cost of the power provided through the solar array compared to that provided by the electric utility.
“We pay 7.66 cents per kilowatt hour to Tucson Electric Power for a melded rate throughout the year,” he says. “Our purchase power agreement with Sun Edison is 4.5 cents per kilowatt hour during the first year with a 1.5-percent annual escalator in the rate.”
Noble says the base anticipates it will save $500,000 a year because of the solar array.
Nationwide, the U.S. Air Force is the largest consumer of energy in the federal government, spending more than $9 billion annually in electricity and fuel costs. It has worked to reduce energy consumption through various initiatives, including renewable energy sources such as the Davis-Monthan solar array, with a stated goal to increase the Air Force’s renewable energy consumption to 25 percent by 2025.
“When you look at the money saved over 25 years, its incredible and also critical to our mission, not only to Davis-Monthan but also to the Department of Defense,” says Col. Kevin E. Blanchard, 355th Fighter Wing commander at Davis-Monthan. “We are looking across the DoD right now for every avenue that we can find to save money and put that money into readiness and sustainment of our force. By saving money on Davis-Monthan’s electric bill, that will help the future of our Air Force, the greatest air force in the world.”
Davis-Monthan AFB isn’t a stranger to solar installations. The base has a number of 10 kilowatt and 20 kilowatt rooftop and ground mounted solar systems on dormitories and other housing, Noble observes.
“The majority of our MilCon construction is commercial and industrial,” he says, including structures such as hangars, simulators, pump housing and administrative buildings. These structures also use an assortment of rooftop and ground mounted arrays and all are built to LEED (Leadership in Energy and Environmental Design) Silver Status.
Noble points out there is another environmental element to the base’s solar array project — it saves 16 million gallons of water annually that would have gone into a cooling tower at a Tucson Electric Power generating plant to produce electricity that would have been consumed by the base.
About the author: Alan M. Petrillo is a Tucson, Ariz., journalist who writes for national and regional magazines and newspapers. He’s also the author of the mystery, Full Moon, books on historical military small arms, and the nonfiction work, Ice Hockey in the Desert.