Scientists make solar cells more efficient and affordable

University of New South Wales researchers have boosted the efficiency of solar cell technology, besides making it much cheaper for commercial use.

Washington, May 4 : University of New South Wales researchers have boosted the efficiency of solar cell technology, besides making it much cheaper for commercial use.

The breakthrough, researchers said, could see the price of an installed solar system for an average house fall from around 20,000 to 15,000 dollars.

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.

In a bid to drive down costs, scientists have moved from using expensive thick silicon "wafers" to "thin film" cells, containing less silicon.

However, there is a disadvantage in these one-to-two micron-thick films, in that they convert only eight to 10 percent of incoming sunlight into electricity, compared to the 25 percent efficiency of thicker, more expensive, silicon wafers.

Now, researchers at the university's ARC Photovoltaics Centre of Excellence have reported a 16-fold enhancement in light absorption in 1.25-micron thin-film cells for light with a wavelength of 1050 nm.

The researchers have devised a way to deposit a thin film of silver (about 10 nanometres thick) onto a solar cell surface and then heat it to 200� Celsius. This breaks the film into tiny 100-nanometre "islands" of silver that boost the cell's light trapping ability, thereby boosting its efficiency.

The scientists have also reported a seven-fold enhancement in light absorption in the more expensive wafer type cells light wavelengths of 1200 nm.

They have said the "new technique could increase efficiency to between 13 and 15 percent".

"Most thin-film solar cells are between eight and 10 percent efficient, but the new technique could increase efficiency to between 13 and 15 percent," said Dr Kylie Catchpole, co-author of the study.

"That's an important advance. 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 per cent efficiency, it becomes commercially viable," she said.

"An average house could have its daily power supplied by installing a solar system and panels covering 10 square metres. 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. Currently only 30,000 Australian households - out of 8 million - have installed solar panels," she added.

The findings appear in the upcoming issue of the Journal of Applied Physics.

ANI