Optical Cavity Furnace Will Make Solar Power Cheaper


Scientists from the U.S National Renewable Energy Laboratory (NREL) have developed a new furnace system for manufacturing solar cells they say could cut the cost of producing solar panels in the future.
The Optical Cavity Furnace (OCF) is designed to replace the standard convection-heating furnaces scattered along solar cell assembly lines. As NREL principal engineer Bhushan Sopori explains, these furnaces blast intense heat – up 1000 degrees Celsius – which is used to remove impurities from silicon solar wafers. Different cell types require different heat treatments, requiring separate furnace systems.
The OCF system can be programmed to fit a specific solar cell configuration and temperature profile. But the real game-changer , according to the NREL, is the use of tailored optics, or photonics, to heat and purify solar cells at unmatched precision while sharply boosting the cells’ efficiency. 
"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," Sopori says. "That’s huge."
Inside the OCF chamber, a combination of infrared and ultraviolet light is used to heat the solar cell in a precise and uniform way. The chamber itself is insulated using highly reflective ceramic blocks, virtually eliminating heat loss. So targeted is the photonic system that the cavity inside the OCF functions "like a microwave", with heat only reaching the wafer inside, not the chamber.
Sopori and his team are currently working with private partners AOS Inc., on building a manufacturing-scale model of the OCF system that could produce up to 1200 solar wafers per hour. Able to do the same job in the quarter of the time of standard heat-treatment systems, OCF seems bound to be another money-spinner on a long list of innovations from the NREL – and another step towards reaching President Barack Obama’s target of 80 percent renewable energy by 2030. 
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