California’s General Hydroponics, Inc. will save roughly 60 percent on its gas and electric bill, thanks to the new Cogenra Solar system on the rooftop of its new Santa Rosa facility. Cogenra’s system combines a reflective trough with conventional photovoltaic cells and a solar-hot water heating component.

The 75-kilowatt system has 15 kilowatts of photovoltaics, and the equivalent of 60 kilowatts thermal energy.

“General Hydroponics is first we’ve announced with the rooftop addition,” said Preston Roper, chief marketing officer at Congenra.

Cogenra last year installed a ground-mounted system at Sonoma Wine Co’s vineyards in California. But this is the first time they’ve taken the technology and adapted it to a rooftop, Roper said.

“Over the next couple of months, you’ll probably see more projects,” he said.

The projects will be in the health care sector, multi-family, military, corporate cafeterias, and at some more commercial applications, like food, beverage and pharmaceutical, application, according to Roper.

The device is capable of getting four times the energy out of the sun that conventional photovoltaics can get on their own, Roper said. The back of the device features an extruded aluminum channel to cool the photovoltaics down, helping them be more efficient than they otherwise would be. A liquid, like a poly glycol, is used to transfer that heat to a heat exchanger where it heats water for use on the premises.

The hot-water component ties into the existing hot-water system, according to Roper.

“While we collect a lot of heat, we can’t control the weather,” he said. “We have some storage, a day or more. During extended periods of inclement weather, the host may need to use their own hot-water heater.”