Arizona Public Service, SunEdison Announce Construction of 10-Megawatt Solar Power Plant in Prescott, Ariz.

PRESCOTT, Ariz., Dec. 17, 2010 /PRNewswire/ -- SunEdison, a subsidiary of MEMC Electronic Materials Inc. (NYSE: WFR), and Arizona Public Service Co., today announced the planned construction of a utility-scale photovoltaic solar power plant to be located two miles north of the Prescott Regional Airport. SunEdison will own and operate the plant with APS purchasing the entire output. APS estimates the 10-megawatt facility can provide enough power to meet the annual energy needs of 2,500 Arizona customers.

The announcement event, to be held at the Hassayampa Inn in Prescott, will spotlight the new solar deployment, which is anticipated to become active in the fall of 2011. The plant is expected to generate more than 25 million kilowatt-hours (kWh) of clean energy in its first year of operation alone and approximately 653 million kWh over 30 years.

"APS's investments in renewable energy – well-diversified by technology, ownership, size and location – are forging a sustainable energy future for Arizona," said Don Robinson, APS President and Chief Operating Officer. "With five solar facilities operating or under construction, Prescott is becoming an important hub for solar development. It is an ideal location because of its abundant sunshine, cooler weather, available land and access to the transmission system."

APS's decade-long history of solar in Prescott includes a 194-kilowatt system at Embry Riddle Aeronautical University (completed in 2001), a small system on the roof of Prescott College (completed in 2004) and a 3.6-megawatt plant near the Prescott Regional Airport (completed in 2006).

Earlier this month APS and SunEdison announced plans for two other Arizona solar plants, a 20-megawatt facility in Chino Valley – another Prescott-area solar plant – and a 17-megawatt facility in Hyder. Those plants also will be developed by SunEdison. However, instead of purchasing the power, APS will own the facilities after construction is completed. With these two solar plants plus today's announcement, APS's renewable portfolio totals approximately 851 megawatts, of which 282 is in operation and serving customers.

"SunEdison offers smart, cost effective, solar solutions that utilities have come to expect and trust," said Carlos Domenech, President of SunEdison. "We have a global demonstrated utility track record and welcome the opportunity to partner with a progressive utility like APS."

About SunEdison

SunEdison is a global provider of solar energy services. The company develops, finances, installs and operates distributed power plants using proven photovoltaic technologies, delivering fully managed, predictably priced solar energy services for its commercial, government and utility customers. In 2009, SunEdison delivered more kilowatt hours (kWh) of energy than any other solar services provider in North America. For more information about SunEdison, please visit www.sunedison.com.

About MEMC

MEMC is a global leader in the manufacture and sale of wafers and related intermediate products to the semiconductor and solar industries. MEMC has been a pioneer in the design and development of wafer technologies over the past 50 years. With R&D and manufacturing facilities in the U.S., Europe and Asia, MEMC enables the next generation of high performance semiconductor devices and solar cells. With the acquisition of SunEdison, MEMC is now a developer of solar power projects and North America's largest solar energy services provider.

MEMC's common stock is listed on the New York Stock Exchange under the symbol "WFR" and is included in the S&P 500 Index. For more information about MEMC, please visit www.memc.com.

About APS

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).

Forward-Looking Statements

Certain matters discussed in this press release are forward-looking statements, including that once completed, the 10-megawatt facility is estimated to provide enough power to meet the annual energy needs of 2,500 Arizona customers; that the deployment is anticipated to become active in the fall of 2011; that the plant is expected to generate more than 25 million kilowatt-hours (kWh) of clean energy in its first year of operation alone and approximately 653 million kWh over 30 years. Such statements involve certain risks and uncertainties that could cause actual results to differ materially from those in the forward-looking statements. Potential risks and uncertainties include delays or interruptions in construction or deployment; the timely availability of required permits and authorizations for projects from governmental entities and third parties; changes in applicable regulatory requirements and incentives for production of solar power; general business and economic conditions, including seasonality of the industry; and other risks described in MEMC's filings with the Securities and Exchange Commission, including its Form 10-K for the 2009 fiscal year and its quarterly reports on Form 10-Q for the first, second and third quarters of 2010. These forward-looking statements represent MEMC's and SunEdison's judgment as of the date of this release. MEMC and SunEdison disclaim, however, any intent or obligation to update these forward-looking statements.

SOURCE SunEdison