Indian-origin scientists new approach to make cheaper, more efficient solar cells

September 15th, 2008 - 6:49 pm ICT by ANI  

Washington, September 15 (ANI): An Indian-origin mechanical engineer and his colleagues at the University of Utah have developed a new approach to slice thin wafers of the chemical element germanium, so that they can be used in the most efficient type of solar power cells.
Dinesh Rakwal, a doctoral student in mechanical engineering, believes that the new method can lower the cost of such cells by reducing the waste and breakage of the brittle semiconductor.
While the present-day expensive solar cells are used mainly on spacecraft, the researchers say that with the improved wafer-slicing method, “the idea is to make germanium-based, high-efficiency solar cells for uses where cost now is a factor,” particularly for solar power on Earth.
“We”re coming up with a more efficient way of making germanium wafers for solar cells to reduce the cost and weight of these solar cells and make them defect-free,” Rakwal said.
Rakwal and Eberhard Bamberg, an assistant professor of mechanical engineering, describe their method as wire electrical discharge machining (WEDM).
The researchers say that their method wastes less germanium and produces more wafers by cutting even thinner wafers with less waste and cracking.
They add that the method uses an extremely thin molybdenum wire with an electrical current running through it.
According to the researchers, it has been used previously for machining metals during tool-making.
Germanium serves as the bottom layer of the most efficient existing type of solar cell, but is used primarily on NASA, military and commercial satellites because of the high expense. Four-inch-wide wafers used in solar cells cost 80 to 100 dollars each.
Grant Fines, chief technology officer for germanium wafer-maker Sylarus Technologies in St. George, Utah, says that the new cutting method may reduce the cost by more than 10 percent.
“Anything that can be done to lower this cost ultimately will lower the cost of solar power per kilowatt-hour, which is beneficial,” and will encourage wider use of solar power, he adds.
“That’’s why this technology Ebbe has come up with is very intriguing,” he says.
“(Bamberg’’s method would) reduce the amount we have to recycle and increase the yield. It has the potential to give good savings, which helps enable this technology here on Earth,” he adds.
Bamberg says germanium-based solar cells are used on most spacecraft because they are more efficient and lighter than silicon-based solar cells.
By making it more attractive economically to use efficient germanium solar cells on rooftops, the weight and size of solar panels can be reduced “so it doesn”t bother you aesthetically,” he adds.
The new method may make germanium-based solar cells competitive with less efficient but less expensive silicon-based solar cells for uses on Earth, adds Bamberg.
Rakwal and Bamberg are publishing their work in the Journal of Materials Processing Technology. (ANI)

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