Solar Energy

With more than 300 sunny days a year, Arizona has an abundant natural resource. APS is working to harness that energy and develop technologies that can make solar power a more viable and affordable energy resource.

In 2005, APS received a "Crescordia" award from Valley Forward for its Solar Test and Research (STAR) Center in Tempe, Arizona. STAR won this award as the top honor in the Arizona private sector environmental technologies category. The STAR Center is one of the world’s premier solar test and research facilities. At STAR, APS tests and develops technologies for converting solar energy into electricity, using current and emerging photovoltaic solar technologies.

APS Solar Generation

APS now has more than 5 MW of installed solar capacity statewide. APS' distributed generation capacity currently comes from our solar energy facilities installed at customer locations. Below are some of the solar power plants that APS currently has in operation.

• Flagstaff- The Flagstaff solar power plant inaugurated the APS Solar Partner^® Program. The Flagstaff plant is housed within the APS service yard and produces 82 kilowatts of solar energy. Built in 1997, the plant employs the use of single axis tracking technology to maximize the sun’s energy.
• Glendale- The City hosts APS' first commercial application of high-concentration photovoltaic arrays at the Glendale Municipal Airport. This technology tracks the sun’s movement and employs special lenses to concentrate the sun’s rays 250 times onto each solar cell.
• Gilbert- The 125-kW plant is adjacent to the Town’s original ground water recharge site. The one-acre site consists of 10 solar arrays, which will track the sun from east to west on a single axis. Each solar array (or series of panels) is about 150-feet long and eight-feet wide and sits relatively low to the ground.
• Prescott- APS and Embry Riddle Aeronautical University joined to construct a 190-kW plant, which feeds solar power to the electric grid. The plant uses a single axis tracking system that allows the photovoltaic arrays to track the sun through the sky. The plant was dedicated in April 2001. 
• Prescott Airport Solar Plant - APS and the City of Prescott teamed to build a plant near the Prescott Airport which currently produces 3.5 MW of solar energy. Upon completion, the plant will produce 6.2 MW, making it one of the world's largest photovoltaic plants.
• Scottsdale- In 1999, the City of Scottsdale formed a unique alliance with APS in an effort to meet the need for covered parking at commercial buildings with a practical way of generating clean energy. An 8,500-square-foot parking structure covered with photovoltaic panels began generating 34 kW of solar energy at a City of Scottsdale service yard.
• Scottsdale Water Campus - APS and Scottsdale officials joined to build a single-axis tracking, photovoltaic plant atop of the City's domestic water tanks which produces 230 kW of solar energy.
• STMicro Rooftop Solar System -This system was the first solar application in Arizona installed for commercial grid-connected customers.
• Tempe- Located on the grounds of the APS Solar Test and Research Center (APS STAR Center^®) in Tempe, this solar plant generates 480 kW of solar energy for use by all APS customers.
• Yuma- APS built a new solar power plant near Yuma, which will generate 100 kW of energy. The plant is located at the Yucca Power Plant and will generate enough energy to serve about 31 homes.
• Phoenix- The Arizona Department of Environmental Quality (ADEQ) hosts a 127-kW flat panel solar plant built atop the facility's parking canopy. The facility is a partnership between ADEQ and APS that makes the facility one of the most energy efficient of all City facilities.

Solar Trough Project

In 2005, APS completed construction and began operation of a 1-MW solar trough plant adjacent to our Saguaro Power Plant about 30 miles north of Tucson. This is the first commercial solar trough power plant in Arizona and the first in the United States in over 15 years. APS contracted with Solargenix Energy for design and construction of the facility.

The cost to APS for this project is about $6 million and is expected to produce about 2,000 megawatt-hours of energy per year. The parabolic mirrors in the plant concentrate the sun 30 to 60 times its normal intensity onto a receiver pipe along the focal line of the trough. Synthetic oil circulates through the pipe capturing the heat, reaching temperatures of 250 to 550 degrees. The hot oil is then pumped through a heat exchanger on the power production side of the plant to produce pentane vapor. The vapor powers a small, compact turbine and is then condensed back to pentane fluid. The use of pentane on the power production side is a unique aspect of the plant enabling smaller turbines, usually associated with geothermal generation plants, to be used.

Solar trough technology is ideally suited for plants in the 50- to 100-MW range. APS' 1-MW plant is intended to demonstrate that the technology is viable in hopes of enabling the development of larger plants in the future. 

Customer Solar Programs

APS Solar Partners Program
Under the Solar Partners Program, APS customers are invited to purchase 15 kilowatt-hour blocks of energy generated by the solar power plants. The cost to customers is a $2.64 per month premium. Solar Partners offers residential and business customers an affordable way to take advantage of the state’s most abundant source of renewable energy, the sun, while helping APS develop a secure energy source for our future. At year’s end, APS had more than 5,000 Solar Partners.

APS EPS Credit Purchase Program
APS offers a credit purchase program to customers buying and installing solar systems. Under the program, the company pays customers $4 per watt – up from $2 per watt in 2002 – for solar systems that are tied to APS’ electric grid, for up to 50 percent of the system’s cost. After consultation with solar vendors in Arizona, APS plans to propose to the ACC that this payment be set at $3 per watt starting in 2006. For these payments, APS receives the renewable energy credits generated by these systems.

To date, 153 customers have installed 704 kW of grid-tied PV systems, and 245 customers have installed 397 kW of off-grid PV systems. In addition, since 2003, APS has purchased EPS credits from customers who have installed solar water heating systems. Since the program started, 209 systems have been installed offsetting an estimated 495 kW of conventional generation.