Another satisfied Unisolar/SIT customer, who will now be a new "word of mouth" salesman......
Co-op adds high-tech solar roof
By Cory Golden/Enterprise staff writer
Eric Stromberg glanced at an aerial photo of Davis on his computer monitor.
"Look at all these roofs - the apartment buildings, the university," Stromberg said Tuesday. "Just think if every flat roof had this sort of generating capacity."
Imagine, in other words, if they all those roofs had new, cutting-edge, photovoltaic solar-electric roofs, like the one recently installed at the Davis Food Co-op, where Stromberg works as general manager.
The new 30.7-kilowatt roofing system should produce enough electricity to power 14 residential homes. It was manufactured by Los Angeles-based Solar Integrated Technologies and installed by Scholten Roofing Service of Sacramento.
Scholten Roofing estimates the system, believed to be the first of its kind in Northern California, will prevent 58,169 pounds of carbon dioxide pollution and 17.4 pounds of nitrous oxide pollution per year.
The new roof panels, made of a thin-film silicon, take advantage of a wider spectrum of light than traditional solar panels. Tests have showed they outperform crystalline modules by up to 30 percent.
The light, long and flexible panels are laminated to a water-tight white vinyl membrane, a material first developed to act as a pond liner, which also acts as a "cool roof," reflecting heat away from the building. The Co-op's new roof also includes 20 skylights that allow little heat in and, for the first time, the roof is insulated.
The old roof was stripped to the plywood, insulation and electrical conduits installed, then sheets of membrane welded on.
Before this spring, the original flat roof of the 1960s era, 27,000-square-foot Co-op building at 620 G St. had never been replaced. It had received its share of major repairs from time to time, but employees don't have to strain to recall putting 10 or more buckets out to catch dripping water or climbing to the roof to sweep away puddles.
Contacted by Stromberg, Wayne Scholten, who had done repair work on the building before, suggested the Co-op take a look at Solar Integrated's Web site.
The store manager did, and came away impressed: "I thought, wow, this is really cool."
Stromberg later joined a representative of the Co-op's board of directors on a trip to Southern California, where they looked at buildings owned by Frito Lay and Coca-Cola Bottling Co. of Southern California featuring the new solar systems. At some warehouses, the roofs produced 60 percent or more of the needed electricity.
Stromberg said the Co-op's board loved what it heard, too, not just because it fulfilled the Co-op's mission to be a leader on environmental issues - but because the roof made good financial sense.
"They're very happy," Stromberg said of the board members. "As trustees, it's their job to maintain our assets. We were able to put on a very high-quality roof and, after the rebate, the cost of the solar portion wasn't that great. How could we not?"
The project cost $299,325, according to Co-op financial manager Kenna Krueger. But that's before the California Public Utilities Commission rebate of $138,150 and federal and state tax credits worth more than $40,000.
Tack on the estimated utility bill savings of $7,590 per year, then figure in the cost of a normal roof guaranteed for 20 years and Krueger estimates the Co-op's new roof should pay for itself in just over two years' time.
Unlike those 14 hypothetical single-family homes, the Co-op uses power in a big way: Its annual electrical bills have topped $160,000.
But when the new system was installed, the store also kept a 3-year-old, 5-kilowatt system of 48 solar panels on a portion of its roof.
Together, the systems could supply about 6 percent of the store's projected annual energy usage, at an estimated savings of $8,760 - and that's not counting the energy use spared by the new insulation.
Plus, there's the way the new roof also will boost employee job satisfaction.
"We won't have to say, 'Put this bucket there' or have water dripping on their heads," Stromberg said, smiling.
The new system isn't visible from the parking lot and the new electrical box is out of site, but Stromberg said he hoped people in the area will want to find out more about the roof.
"Anybody who wants to can come take a look at it," he said. "You just need to be able to climb a ladder."
- On the Web: solarintegrated.com, daviscoop.com., scholtenrfg.com.
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