Solar Energy Creeping Its Way Over the Horizon

Solar energy could become more affordable, following a breakthrough by Australia’s University of New South Wales (UNSW) scientists who have boosted the efficiency of solar cell technology. The advance could see the price of an installed solar system for an average house fall to around $15,000 from $20,000.

Up to 45 percent of the cost of solar cell technology is due to the high cost of the silicon used to convert sunlight to electricity. However, silicon is a poor absorber of light. In a bid to drive down costs, scientists have moved from using expensive thick silicon “wafers” to cheaper “thin film” cells, containing less silicon. The disadvantage of these 1-to-2 micron-thick films is that they convert only 8 to 10 percent of incoming sunlight into electricity, compared to the 25 percent efficiency of thicker, more expensive, silicon wafers.

Now, researchers at UNSW’s ARC Photovoltaics Centre of Excellence, led by Ph.D. student Supriya Pillai, have reported a 16-fold enhancement in light absorption in 1.25-micron thin-film cells for light with a wavelength of 1,050 nm. They also have reported a seven-fold enhancement in light absorption in the more expensive wafer type cells with light wavelengths of 1,200 nm.

“The new technique could increase efficiency to between 13 and 15 percent,” said Kylie Catchpole, a co-author of the study. That’s an important advance, she said. “If they’re below 10 percent efficient, then you can’t really afford to install them because it would take up too much of your roof area, for example, to power your house.”

Once the technology approaches 15 percent efficiency, it becomes commercially viable. An average house could have its daily power supplied by installing a solar power system and panels covering 10 square meters. This system would exclude power for cooking and hot water heating.

The breakthrough could eventually see a dramatic rise in solar power’s share of the electricity market.      EC



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