North Carolina’s mandated march toward use of renewable energy supplies made a small but significant step forward this week.

Despite often cloudy and rainy weather, literally turned on the five-acre solar panel built at its Cary campus and begin feeding power to the grid. Progress is buying the energy, but neither company is disclosing the price.

The solar “farm,” which is a vast collection of panels designed to capture and convert sun power to electrical power, is the first to be brought online by Progress. Progress and other utilities are required by state law to begin producing power from renewable sources with solar to account for a minor percentage of that by 2010.

Another solar farm is being built in Wilmington, and scores of others are under consideration, according to Progress.

“This is a huge milestone,” said Progress spokesperson Mike Hughes. “We truly need a 100 projects like it or to build on this and get even larger projects.”

The photovoltaic site, built by , has a capacity of 1 megawatt and is expected to produce 1.7 million kilowatt hours of power a year. That’s about enough to provide electricity for a little over 100 homes, based on the average customer use of 14,000 kilowatts of electricity a year, Hughes said.

In the grand scheme of power generation, the SAS project is minuscule. Currently Progress has 12,400 megawatts of generating capacity in the Carolinas alone.

The solar panels are equipped with technology that enables them to track the sun, but they are expected to produce power between 16-20 percent of each day, he added. SunPower built a similar site in New Jersey.

Regardless of size or capacity, SAS Chief Executive Officer Jim Goodnight hailed the sight’s official generation of power.

“In less than a year this plan went from idea to reality,” he said in a statement. “I hope people will learn from our experience that sustainable energy is within reach and makes bottom-line business sense.”

SAS recently announced plans for a new office building that will be designed to save energy. The company also plans other campus upgrades to reduce energy use.

The world’s largest privately held software campus has not allowed visitors to the solar farm and also declined to allow photographs.

“Sorry, the site is not going to be available for public viewing for a few weeks,” SAS spokesperson Dave Thomas said. “I know that seems odd considering that we issued a release but we just want to have it presentable before we bring people out.”

Progress Energy is exploring solar, wind, biowaste and other options to produce power from renewable sources. By 2012 state law mandates that 3.5 percent of all retail sales come from so-called renewables. That percentage jumps to 12.5 percent by 2021.

Duke Energy is also involved in numerous solar and wind projects.