Australians set another world record

Not at the Olympics, but in solar cell efficiency.

 A new solar cell configuration developed by engineers at the University of New South Wales has pushed sunlight-to-electricity conversion efficiency to 34.5 per cent – establishing a new world record for unfocused sunlight and nudging closer to the theoretical limits for such a device. The record was set by Dr Mark Keevers and Professor Martin Green AM, Senior Research Fellow and Director, respectively, of UNSW’s Australian Centre for Advanced Photovoltaics. They used a 28-cm2 four-junction mini-module – embedded in a prism – that extracts the maximum energy from sunlight by splitting the incoming rays into four bands, using a hybrid four-junction receiver to squeeze even more electricity from each beam of sunlight.

 Dr Mark Keevers and Prof Martin Green

Dr Mark Keevers and Prof Martin Green

The new UNSW result, confirmed by the US National Renewable Energy Laboratory, exceeds the previous record – made by Alta Devices of the US, which reached 24 per cent efficiency, but over a larger surface area of 800-cm2.

The result was obtained by the same UNSW team that set a world record in 2014, achieving an electricity conversion rate of more than 40 per cent by using mirrors to concentrate the light – a technique known as CPV (concentrator photovoltaics) – and then similarly splitting out various wavelengths. The new result, however, was achieved using normal sunlight with no concentrators.

“This encouraging result shows that there are still advances to come in photovoltaics research to make solar cells even more efficient,” said Dr Keevers. “Extracting more energy from every beam of sunlight is critical to reducing the cost of electricity generated by solar cells as it lowers the investment needed, and delivering payback faster.”

“What’s remarkable is that this level of efficiency had not been expected for many years,” said Professor Green, a pioneer who has led the field for much of his 40 years at UNSW.

 “So things are moving faster in solar cell efficiency than many experts expected, and that’s good news for solar energy,” he added. “But we must maintain the pace of photovoltaic research in Australia to ensure that we not only build on such tremendous results, but continue to bring benefits back to Australia.”

 Australia’s research in photovoltaics had already generated flow-on benefits of more than $8 billion to the country, Professor Green said.

 The 34.5 per cent result with the 28 cm2 mini-module is already a world record, but scaling it up to a larger 800-cm2 is well within reach. “There’ll be some marginal loss from interconnection in the scale-up, but we are so far ahead that it’s entirely feasible,” Dr Keevers said.

The research is supported by $1.4 million grant funding from the Australian Renewable Energy Agency (ARENA). Other partners are another ARENA-supported company, RayGen, Trina Solar, a PV module manufacturer, and the U.S. National Renewable Energy Laboratory.

Professor Green is a Fellow of ATSE. His research has been highlighted in these STELR News items from 2015:

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