ESCONDIDO -- Stone Brewing Co., maker of challenging beers with a high hoppy kick, plans to install a $3.2 million photovoltaic system in its brewery/restaurant.

The electricity-producing system is scheduled to be installed by February and pay for itself in 10 years, said Greg Koch, Stone's chief executive, in an interview last week. He estimates the 360-kilowatt system will provide up to 54 percent of the company's power needs.

Stone Brewing is installing the system to demonstrate its commitment to the environment, said Koch (pronounced "Cook"). But it also makes sense financially, he said.

"When you get to the $3.2 million this thing is going to cost, you've got to have business needs in the equation," Koch said by telephone from the Great American Beer Festival in Denver.

Stone Brewing uses much of its electricity refrigerating the beer it brews on the premises, Koch said, pausing to draw breath while walking through the Mile High City.

"Our 8,000-square-foot cold box is definitely a big energy draw," Koch said. "Then it's kind of all over the map for the rest of the things that we do, from the brewing process to the bottling and packing needs."

The company shows its environmental credentials in other ways, such as using biodiesel to power its delivery trucks. Biodiesel is a fuel made from vegetable or animal oils and is considered a renewable resource. It can be used in unmodified diesel engines.

Koch said Stone tried to incorporate solar power into its headquarters in the Escondido Research and Technology Center, which it began occupying in 2005, "We did our best during construction of the building but were unable to put it together."

Stone finally found the right company and system with Borrego Solar Systems Inc. of El Cajon, Koch said. The particular system Stone chose uses a newer and more efficient technology, called Heterojunction With Intrinsic Thin Layer.

The plan for the Stone Brewing World Bistro & Gardens includes carports roofed with photovoltaic units, serving two purposes at once: shade and power. The complex began as a new brewery for Stone, which had been located in San Marcos. Last year, the company opened a restaurant on the premises, with outdoor and indoor dining.

Stone Brewing can be reached at (760) 471-4999 or on the Web at (http://www.stonebrew.com).

Contact staff writer Bradley J. Fikes at (760) 739-6641 or bfikes@nctimes.com.