An Australian team has set a new record for squeezing as much electricity as possible out of direct, unfocused sunlight via a new solar cell configuration. Engineers at the University of New South Wales (UNSW) achieved 34.5 percent sunlight-to-electricity conversion efficiency, a new mark that also comes closer than ever to the theoretical limits of such a system.
UNSW's Dr. Mark Keevers and Professor Martin Green set the record with a 28 centimeter-square (4.3 sq in), four-junction mini-module embedded in a prism. This new configuration allows the sun's rays to be split into four bands so that a higher amount of energy can be extracted from each beam.
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The same team reached an even higher level of efficiency a few years back using mirrored concentrators that were able to convert 40 percent of incoming sunlight to electricity. However, this new record is the highest level achieved without the use of concentrators.
"What's remarkable is that this level of efficiency had not been expected for many years," said Green, citing a German study that set a goal of 35 percent efficiency to be reached by 2050.
The team does not expect that its record-breaking cell configuration will find its way on to home or office rooftops anytime soon, as they are more costly to manufacture. The group is working to reduce the complexity to make them cheaper to produce and sees a future for them on solar towers that make use of concentrating mirrors.
Meanwhile, efficiency gains are also being made in the development of organic solar cells that are cheaper and more flexible. There's still a long way to go though, as the most recent record for organic photovoltaics set in February was 13.2 percent efficiency.
Source: University of New South Wales