Two New Solar Power Plants to be Located in Arizona

Located in Hyder (40 miles east of Yuma) and Chino Valley (15 miles north of Prescott), the two solar energy plants will bring APS’s renewable energy portfolio to nearly 682 megawatts by 2013 (including projects currently online or in development).

The 17-megawatt Hyder solar plant and the 20-megawatt Chino Valley solar plant are part of APS’s AZ Sun program. Through this program, APS plans to develop 100 megawatts of utility-owned photovoltaic power plants using a procurement model where a third party builds the solar plant and APS takes ownership when it goes into commercial operation.

“These two solar projects will further increase the resource and geographic diversity of our energy supply, and under the AZ Sun program they will also provide ownership diversity,” said Don Robinson, APS President and Chief Operating Officer. “By adding layers of diversity to our energy supply, we are reducing our fuel cost risk and increasing energy security for our customers. We also are providing another substantial boost to Arizona’s growing renewable energy industry.”

With the two projects announced today, AZ Sun has 70 megawatts in development.

Construction on the Hyder plant is expected to begin in June 2011, with an in-service date expected in the fourth quarter of 2011. Construction on the Chino Valley project is expected to start in the first quarter of 2012, with completion expected in the fourth quarter of 2012. Both facilities will use polycrystalline photovoltaic panels mounted on single-axis tracking systems.

“SunEdison continues to make large-scale solar generation a reality for utilities worldwide,” said Carlos Domenech, President of SunEdison. “With a solid track record, SunEdison is a proven choice for utility-scale solar deployment and is proud to be working with APS to help the company reach its renewable energy goals.”

SunEdison is a leading worldwide solar energy services provider and a subsidiary of MEMC Electronic Materials (NYSE: WFR).

In 2010 the Arizona Corporation Commission approved the AZ Sun program. APS’s other two AZ Sun projects, a 15-megawatt installation at Luke Air Force Base and an 18-megawatt project in Gila Bend, are both scheduled to come online in 2011.

APS, Arizona’s largest and longest-serving electric utility, serves more than 1.1 million customers in 11 of the state’s 15 counties. With headquarters in Phoenix, APS is the principal subsidiary of Pinnacle West Capital Corp. (NYSE: PNW).