Solar Energy Reaches a New Efficiency Record

Correction: As originally published, this story suggested that researchers had found a way to produce a solar cell that outputted more energy than it took in. Instead, researchers improved the external quantum efficiency of solar cells, which is essentially the rate of electrons flowing out of a solar cell divided by the rate of photons flowing in. It should not be confused with the "actual" efficiency rate--the laws of physics dictate that it can't output more energy than it takes in. Also, it should be noted that this is "peak" quantum efficiency, as a reader has pointed out, not a sustained quantum efficiency level. We apologize for the confusion and regret the error. The corrected story follows below.

Scientists have figured out a way to greatly increase the efficiency of solar cells, which could help make solar energy a viable alternative to fossil fuels. However, MIT's Technology Review highlights a political tug-of-war between China and the United States that could actually make the photovoltaic technology too expensive to market. As a result, energy that should be globally affordable in the near future might just be out of reach.

Just this past week, PhysOrg reported that researchers at the National Renewable Energy Laboratory (NREL) had finally crafted a solar cell with a extetnal quantum efficiency (EQE) value of over 100 percent. Basically, EQE measures the rate of energy flowing out of a solar cell divided by the rate of light flowing into it.

This shouldn't be confused with a solar cell putting out more energy than it takes in, as this would violate the Law of Conservation of Energy. But for non-phycists, the takeaway is that, with these new developments, solar cells should eventually be able to do their job a lot better.

Researchers achieved this thanks to some inventive applications of zinc oxide, lead selenide, and a touch of gold: This new type of solar cell achieves roughly "114 percent external quantum efficiency", according to PhysOrg. Here are the bare details from PhysOrg, detailing what it means for green, naturally sustainable energy.

"The newly reported work marks a promising step toward developing Next Generation Solar Cells for both solar electricity and solar fuels that will be competitive with, or perhaps less costly than, energy from fossil or nuclear fuels.

"In a 2006 publication, NREL scientists Mark Hanna and Arthur J. Nozik showed that ideal MEG in solar cells based on quantum dots could increase the theoretical thermodynamic power conversion efficiency of solar cells by about 35 percent relative to today’s conventional solar cells. Furthermore, the fabrication of Quantum Dot Solar Cells is also amenable to inexpensive, high-throughput roll-to-roll manufacturing."

Head on over to PhysOrg for more technical details if you want to learn more.

But even if solar energy becomes cheap enough for mass production, MIT's Technology Review notes that trade tariffs could inflate the cost of the technology. In fact, it has already started, as China-based producers of solar cells and energy-collecting modules are selling their products at "unfairly low prices." In retaliation, the U.S. Government has started playing political hardball.

So, what does this mean for the average person who wants to use alternative energy? Without the benefit of global collaboration and affordable solar cells, you're probably going to spend less money sticking to electricity and gas. If that's the case, then you can officially stop saving up for that solar-powered roof you always wanted.

"On October 18, the U.S. government was asked to impose tariffs on imports of Chinese solar cells and modules, based on the argument that China-based producers have been heavily subsidized and are selling solar products at unfairly low prices. Perhaps not surprisingly, some Chinese companies have now asked the Chinese government to impose tariffs on imports of American solar products, arguing that U.S.-based producers have been heavily subsidized, too. And just like that, the production of affordable and competitive solar products has become a political liability in the world's two largest producers and consumers of energy."

[MIT Technology Review, PhysOrg]

Story updated Dec 20, 2011 11:58PM PST to correct factual errors and to clarify some details.

McKinley Noble is a former GamePro staff editor, current technology nerd and eternal mixed martial arts enthusiast. He also likes Japanese sports dramas and soap operas. Follow him on Twitter or just Google his name.

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