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Cogenra Solar concentrator pulls double duty

The Silicon Valley start-up is readying a solar concentrator for producing both electricity and hot water on site.

Martin LaMonica Former Staff writer, CNET News
Martin LaMonica is a senior writer covering green tech and cutting-edge technologies. He joined CNET in 2002 to cover enterprise IT and Web development and was previously executive editor of IT publication InfoWorld.
Martin LaMonica
2 min read

In a glut of solar photovoltaic providers, Cogenra Solar's is trying to ride the solar hot-water wave.

The Mountain View, Calif.-based company, which has been operating in stealth mode since its founding a year and a half ago, today said it received a $1.5 million state grant to test its combined solar electric and hot-water system at a demonstration project at Sonoma Wine Company in northern California.

Before the end of the year, Cogenra Solar will publicly show how the Sonoma Wine installation is using its solar concentrator at "meaningful scale," said CEO Gilad Almogy yesterday. The company is backed by Khosla Ventures which invested $10.5 million last year.

The Cogenra Solar concentrator focuses the light onto a strip of solar photovoltaic cells to make electricity. Behind the solar cells are tubes to capture heat.
The Cogenra Solar concentrator focuses the light onto a strip of solar photovoltaic cells to make electricity. Behind the solar cells are tubes to capture heat. Cogenra Solar

Cogenra Solar is targeting commercial and industrial companies with a need for both on-site electricity and hot water, which could everything from hotels to food-processing facilities. Although hybrid solar electric and hot-water systems have been tried for decades, few companies appear to be marketing to commercial and industrial businesses.

Its trough-shaped solar concentrator tracks the sun during the day and focuses light onto a strip of photovoltaic cells above the trough. By concentrating the light, the solar cells produce more electricity.

Behind the assembly holding the strips of solar cells are tubes that wick away the heat. That heat is then transferred to a tank to preheat water for a traditional boiler. By doing both heat and electricity, the system captures far more available solar energy, according to the company.

The concentrator is made out of readily available materials--silicon, metal, glass--and can be manufactured on existing equipment, which keeps the cost down, Almogy said. Taking into account subsidies, the system could offer a payback of about five years, or about half the time for a commercial solar PV array, he said.

Tax credits and rebates for solar photovoltaics have been in place for some time, but Almogy said that California and European countries are boosting the rebates and subsidies for commercial solar hot water.

Cogenra also plans to offer a power purchase agreement through which a commercial customer doesn't need to pay money upfront. Instead, it agrees to buy the heat and electricity from the solar concentrator at a preset price while the project developer owns and maintains it.

The biggest competition for the company is "status quo," said Almogy. Even though companies can lower their utility bills, most are used to paying electric and heating bills separately and they may not think to install on-site renewable energy.

Updated at 11:00 a.m. PT to clarify that Sonoma Wine is first customer.