Cogenra’s Double Whammy: Solar Arrays that Generate Electricity and Hot Water

7/18/11

A Silicon Valley startup is trying to squeeze more energy out of sunlight by combining photovoltaic arrays with a technology to generate hot water, to lower the costs of both electricity and heat.

Based in Mountain View, CA, and backed venture capitalist Vinod Khosla among others, Cogenra Solar has fielded only two installations thus far. But CEO Gilad Almogy says Cogenra aims at a huge swath of industries and applications that require both electricity and heat, including food processing plants, pharmaceutical factories, hospitals, jails, and apartment complexes.

“Everywhere there is a significant use of heat, our systems make sense,” Almogy said.

The company, formerly known as Skywatch Energy, made a splash in November when former British Prime Minister Tony Blair took part in the unveiling of a Cogenra installation at Graton, CA-based Sonoma Wine Company, which uses the hot water to wash out wine barrels.

Cogenra employs several technical tricks to coax more than 75 percent of the energy from sunlight—most of this in the form of hot water—versus the 20 to 25 percent of an efficient photovoltaic array.

Its systems are long half-cylinders of reflective material that concentrate sunlight on a photovoltaic strip running the long way down the focal point of the array.

In addition to converting part of the sun’s rays into electrical energy, the metal in the photovoltaic strip becomes extremely hot. Cogenra runs water though an insulated metal tube behind the photovoltaic array, thus capturing that heat and using it to warm water to anywhere from 70 to 170 degrees Fahrenheit, depending on customer need.

Cogenra says customers who install its systems qualify for solar hot water system rebates, such as those provided by the California Solar Initiative (CSI), as well as rebates for electricity-generating photovoltaic systems. Taking its thermal and electricity rebates together, Cogenra says some customers could see a full return on their investment in about five years.

Almogy said Cogenra is aiming at the broad middle part of the solar market, in between single-home sites and huge power-plant scale installations.

To facilitate sales, Cogenra is also prepared to offer heat and power purchase agreements, under which it would finance and operate installations in lease-back arrangement with customers. Toward that end it has attracted chief marketing officer Preston Roper, formerly of San Francisco-based Tioga Energy, a solar installer with long experience using purchase power agreements..

In addition to Roper and Almogy—who is a veteran of Applied Materials, the semiconductor tool-maker that has entered the photovoltaic space—other key management players include chief operating officer Ratson Morad, a veteran of Solyndra, another solar startup.

Other backers include Pierre Lamond, a partner at Khosla Ventures, and Dan Maydan, the former president of Applied Materials.

While competitors are also starting to combine thermal heat and photovoltaics into a single system, Almogy said Cogenra is furthest along in certification by standards-setting bodies. He said the 30-person company has other deals in the pipeline, but is not ready to announce them.

Here’s a six-minute video introduction made by Cogenra Solar.

Why Solar Cogeneration? from Stephen Harper on Vimeo.

Tom Abate is a freelance writer in the San Francisco Bay Area who has covered science, high-tech, biotech, and economics. Follow @

By posting a comment, you agree to our terms and conditions.