Manufacturing Solar Cells Just Became 50% More Efficient


solar cell optical furnace nrel

As the New Year gets rolling, consider raising a toast to the National Renewable Energy Laboratory (NREL). Despite suffering repeated funding cuts in recent years, the Department of Energy-funded lab, based in Colorado, has recently been churning out technological breakthroughs at a breakneck pace. Last month, it announced the development of the first solar cell that produces more electrons than it takes in from the sun. It also handed out the first commercial license for innovative, high-efficiency ‘black silicon’ solar technology it developed in 2010.

And another big breakthrough it recently announced is a new method for creating solar cells which looks set to reduce the energy cost of manufacture by 50%.

The primary cost of making solar cells comes from heating silicon, and NREL has developed a new ‘optical furnace’ to achieve the necessary heating more efficiently. Instead of conventional heat, the optical furnace uses intense light, which is easier to focus and direct for minimum waste. It uses “highly reflective and heat-resistant ceramics to ensure that the light is absorbed only by a silicon wafer, not by the walls inside the furnace.”

NREL first announced tests of the optical furnace in October. After testing, they said they expect it to ultimately reduce the energy cost of producing solar cells by up to 50% — likely slashing the financial cost as well.

As if that isn’t exciting enough, the optical furnace also produces cells which are themselves more efficient to use. The laser-like light produced by the furnace removes impurities from the silicon as it shapes it, making for more efficient solar cells as an end product. As NREL reports:

NREL researchers continue to improve the furnace and expect it to be able soon to hike the efficiency by 4 percentage points, a large leap in an industry that measures its successes a half a percentage point at a time. “Our calculations show that some material that is at 16 percent efficiency now is capable of reaching 20 percent if we take advantage of these photonic effects,” NREL Principal Engineer Bhushan Sopori said. “That’s huge.”

NREL’s breakthrough isn’t just good news for solar power generally, but for the US solar industry in particular. US manufacturers have been struggling to cope with rapidly dropping prices for solar cells, thanks to increased activity in the sector by Asian competitors (like iPhone manufacturer Foxconn, which is about to open its first solar modules plant). The September bankruptcy of California’s Solyndra was, of course, 2011’s highest-profile example of this trend. If NREL’s technology becomes commercially available within the next couple of years, it could help the remaining US solar manufacturers compete — unless Asian manufacturers license the technology too, of course.

For more on NREL’s contributions to solar energy research, see Solar Cell with 114% External Quantum Efficiency.

Picture: NREL

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