CARY - Software developer SAS, the town's biggest private employer, will double the size of the solar farm on its corporate campus.

The company plans to build a 1.2-megawatt addition, enough to power about 200 homes, to the existing 1-megawatt facility that began operating in December.

The new solar project is scheduled to begin generating electricity in March.

When combined, the 2.2-megawatt SAS solar project will constitute the state's biggest solar energy farm.

"This solar farm demonstrates SAS' continued commitment to protecting our environmental resources," Jerry Williams, the company's environmental sustainability program manager, said in a statement. "We hope other organizations will see this as an example of what is possible for them."

Charlotte-based Duke Energy, meanwhile, is in the process of building a 16-megawatt solar farm, which will be one of the biggest solar farms in the nation.

The grass on SAS's 12-acre solar farm will be grazed by sheep -- an increasingly accepted environmental practice at solar energy facilities.

Progress Energy has contracted to buy the electricity from the existing SAS solar farm. Plans have not been finalized for the 1.2 megawatt addition. The Raleigh utility is buying solar power and other forms of renewable energy to meet the state's green mandates.

SAS made the announcement Friday, as members of President Barack Obama's cabinet toured the solar farm.

U.S. Interior Secretary Ken Salazar and Energy Secretary Steven Chu were there to tout the expansion of the renewable energy industry.

Southern Energy Management was the primary contractor for SunPower on the existing five-acre, 5,040 panel farm at SAS. The Morrisville company also installed a 24-panel rooftop solar system that provides hot water for a SAS’ cafeteria.

The existing farm includes a 24-collector solar water heating system and a 1-megawatt system of 5,040 solar panels on five acres.

Salazar called the firm one of hundreds of cutting-edge renewable energy companies sprouting up around the country, his department said.

"This is a company whose mission is to reduce carbon emissions that contribute to climate change and to build a sustainable, triple-bottom-line that values people, the planet and profit," Salazar said in a statement.

"Its employees have installed more than 11,000 solar panels, producing about 2.8 million kilowatt hours of clean energy. Their work in 2008 offset more than 74 million pounds of carbon dioxide, the equivalent of planting 5.7 million trees. These folks believe they can help change the world for the better and we couldn't agree more."

The Interior Department is investing $41 million through the economic recovery bill to spur a rapid and responsible move to large-scale production of renewable energy on public lands. Interior also is evaluating 24 solar energy study areas for environmentally appropriate expedited solar energy development.

More than 6,000 megawatts of new capacity -- mostly in California, Arizona, and New Mexico -- could be ready by 2010, according to the department. That is enough to power 1.8 million homes.

SAS' environmental sustainability program also includes two buildings in Cary that are being built to meet the standards of the U.S. Green Building Council.