Flickr photo by Wayne National ForestA new technology could increase solar cell efficiency to rival that of oil.
A major breakthrough in harnessing the sun’s energy has just been announced by a team of Stanford University researchers.
Instead of just harvesting light energy from the sun – or alternatively, just the sun's heat – the researchers found a way to combine the two forms of energy into a highly efficient system.
And they say the technology is so inexpensive it could rival oil.
“It’s pretty darn exciting,” said Sue Kateley, executive director of the California Solar Energy Industries Association. The researchers “took two things and put them together in a new and different way. And the way that they did it is going to have significant cost breakthroughs.”
Most solar cells, such as the ones used on rooftop panels, use silicon to convert sunlight into electricity. But the cells only use a portion of the light spectrum. The rest of the light energy is lost in the form of heat.
In addition, traditional solar cells are intolerant of high heat. They actually stop working as temperatures approach 100 degrees Celsius (or 212 degrees Fahrenheit), irrespective of the amount of light they are receiving.
So, what you have is a system that can’t get too hot, or it won’t work.
This new technology, called photon-enhanced thermionic emission, or PETE, turns this whole paradigm on its head.
Not only does PETE thrive in high temperatures, it also then converts that heat into energy, creating a system that can potentially increase solar efficiency from 20 percent, which is about where it is now, to 60 percent.
"The PETE process could really give the feasibility of solar power a big boost," Nick Melosh, an assistant professor of materials science and engineering, said in a press release. "Even if we don't achieve perfect efficiency, let's say we give a 10 percent boost to the efficiency of solar conversion, going from 20 percent efficiency to 30 percent, that is still a 50 percent increase overall."
And those are the kinds of numbers that could make it competitive with oil.
"This is really a conceptual breakthrough, a new energy conversion process, not just a new material or a slightly different tweak," said Melosh, who directed the project. "It is actually something fundamentally different about how you can harvest energy."
The new cells use a gallium-based semiconductor coated with a thin layer of the metal cesium. And Melosh sees the devices’ potential in large solar concentrators such as parabolic dishes, which can get as hot as 800 degrees Celsius.
The study was published in the journal Nature Materials.
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