Solar Heater/Power System Being Built

A Boulder, Colo., company’s bid to make solar power more viable for residential and small commercial buildings by using it to both heat water and produce electricity appears to be making headway. The company, Cool Energy, announced it has completed commissioning of the solar field for its SolarFlow System on a commercial building.

The idea behind Cool Energy’s work is to take advantage of as much of the energy captured by a solar system as is possible. It tries to do so with its SolarHeart Engine, a generator powered by a Stirling engine that activates whenever the electricity produced from the solar system is more valuable than the heat consumed. So in winterime, most of the energy from the solar field is used to heat a building’s work or living space. Then in summer months, the system’s engine converts that thermal energy to electricity which can be used to power, say, air conditioners.

Solar cogeneration, Cool Energy

image via Cool Energy

The Cool Energy technology looks like a different way to get at the solar cogeneration possibilities being pursued by Cogenera Solar.

The company says that  peak utility electrical loading requirements are better matched with the SolarFlow System than straight solar photovoltaic because the thermal storage feature enables electricity production throughout the day (even when cloudy) and night. According to Cool Energy, tests of the third generation of the SolarHeart “recently generated over 2000 watts of electric power, and reached a thermal to electrical conversion efficiency of over 16 percent, exceeding expectations.”

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.


  • Reply January 26, 2011

    Maxie Coale

    Comment: Using “waste heat” to generate power is a great addition to using solar power. At least during cloudy days and at night, the system can still supply energy. This is a good advancement for the solar industry.

  • Reply April 11, 2011


    When water is needed, the electric water heater is bypassed and the water flows into the house by way of gravity. In order to heat water when the sun isn’t shining, you’ll want to add a backup electrical heating element.

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