Solar Energy Breakthrough: Power from Light AND Heat

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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.