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Published on August 3rd, 2010 | by Zachary Shahan


Solar Energy Breakthrough: Power from Light AND Heat

August 3rd, 2010 by  




What’s one way to make solar power production twice as efficient? Make power from both the sun’s light and its heat. Stanford scientists may have just nailed this one.

“Unlike photovoltaic technology currently used in solar panels – which becomes less efficient as the temperature rises – the new process excels at higher temperatures,” Louis Bergeron of Stanford University News reports.

“Called ‘photon enhanced thermionic emission,’ or PETE, the process promises to surpass the efficiency of existing photovoltaic and thermal conversion technologies.”

Apparently, this is a complete breakthrough. Not an innovation or a simple material replacement.

“This is really a conceptual breakthrough, a new energy conversion process, not just a new material or a slightly different tweak,” said Nick Melosh, assistant professor of materials science and engineering at Stanford University who led the research group. “It is actually something fundamentally different about how you can harvest energy.”

Bonus point: the materials needed for the device are cheap and easily available.

Here is some more background information on the inefficiency being addressed and how PETE is solving the problem:

Most photovoltaic cells, such as those used in rooftop solar panels, use the semiconducting material silicon to convert the energy from photons of light to electricity. But the cells can only use a portion of the light spectrum, with the rest just generating heat.

This heat from unused sunlight and inefficiencies in the cells themselves account for a loss of more than 50 percent of the initial solar energy reaching the cell.

If this wasted heat energy could somehow be harvested, solar cells could be much more efficient. The problem has been that high temperatures are necessary to power heat-based conversion systems, yet solar cell efficiency rapidly decreases at higher temperatures.

Until now, no one had come up with a way to wed thermal and solar cell conversion technologies.

Melosh’s group figured out that by coating a piece of semiconducting material with a thin layer of the metal cesium, it made the material able to use both light and heat to generate electricity.

For more on the PETE process, go to the Stanford University News article.

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About the Author

is tryin' to help society help itself (and other species) with the power of the typed word. He spends most of his time here on CleanTechnica as its director and chief editor, but he's also the president of Important Media and the director/founder of EV Obsession, Solar Love, and Bikocity. Zach is recognized globally as a solar energy, electric car, and energy storage expert. Zach has long-term investments in TSLA, FSLR, SPWR, SEDG, & ABB — after years of covering solar and EVs, he simply has a lot of faith in these particular companies and feels like they are good cleantech companies to invest in.

  • very cool stuff. I am hoping for additional breakthroughs in solar power for a variety of reasons..

  • Wally

    This was patented about 14 years ago ??? The patent
    number is like almost 4000000 or 4000040 something
    like that. It was by two guys in Australia, is what
    I remember.

    The basic claim in the patent is that any device that concentrates the heat is covered.

    If you don’t concentrate the heat, it’s not covered.

  • DMcD

    I’m sure [ ? ] this Stanford ‘breakthrough’ will change the world and all that but….given the (near complete) absence of details in this story, I don’t really see why they bothered releasing this PR in the first place.

    Unlike the missing details in this piece, I’m following another, semi-related, disruptive solar-tech company with a great deal of interest. Quantum Materials Corps’ subsidiary, Solterra Renewable Technologies, appears to really be onto something with their ‘Tetrapod Quantum Dot’ tech.

    Solterra’s TQD semi-conductor applications are primarily aimed at ‘solar’ but go well beyond solar alone. If curious, check the (much more complete) ‘details’, at:

  • poningru

    Can someone give some figures on commercial availability/price of these matierials? On top of that how much cheaper is it to fashion these substances into a solar thermal/pv cell?

    silicon is pretty cheap, it’s getting it into a pure form (>99.9% ) and then forming it into pv cells that is expensive.

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