Santa Clara U. has installed 60 rooftop solar collectors.

If concentrating sunlight works for utility-scale solar power plants, how about for heating and cooling a single building

Santa Clara University, which sits in the heart of Silicon Valley, said yesterday that it has started using 60 rooftop solar collectors atop its student center to concentrate sunlight to generate heat, a technique typically used only for large-scale solar systems.

The solar collectors were developed by start-up Chromasun, which was formed to adapt solar concentrators for commercial rooftops. By heating water to as high as 400 degrees, the solar thermal system can be used for both hot water and to fuel air conditioners for commercial buildings.

The collectors use optics to concentrate sunlight 25 times, allowing them to heat water to 200 degrees. Santa Clara University, which installed the collectors for student center dining services, estimates it will reduce the building's natural gas heating load by 70 percent and offset 34 tons of carbon dioxide per year.

The collectors concentrate sunlight 25 times.

With a California solar rebate program, the return on the initial investment is six years. The university will pay a fixed price for energy from the collectors under a 10-year lease and then own them afterward. The components were manufactured in nearby San Jose.

"The [collector] is visually stunning, is ideal for commercial-scale solar heating and cooling applications, and has an ingenious mounting system that ensures even large-scale systems go in quickly and easily," Justin Weil, the president of SunWater Solar, a solar thermal installation company, said yesterday in a statement.