Leap in efficiency of solar cells predicted by inventor

The inventor of the silicon technology that dominates solar power predicts that combining other materials with the silicon may boost the efficiency of photovoltaic cells from around 25 per cent today to more than 40 per cent.

Martin Green, an engineer and professor of the University of New South Wales, who invented the technology that is used in about 90 per cent of the world’s solar panels, made the prediction in an FT interview in London, where the work was recognised with an accolade for innovation in engineering.

The Perc, or Passivated Emitter and Rear Cell, that was developed by Green and his collaborators, reflects escaping light and electrons back into a photovoltaic cell — and boosts its efficiency from 16.5 per cent to the current 26 per cent, enabling solar power to compete effectively with fossil fuels.

But Perc is approaching the limit of efficiency, Green told the FT. “Perc will probably get over 27 per cent some time this year and it will be the mainstay for solar cells for most of the rest of this decade, but there will be challenges from other technologies down the track.”

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His latest research at the Australian Centre for Advanced Photovoltaics now focuses on “stacked cells”. These layer other materials on top of silicon to maximise the conversion of all wavelengths in sunlight into electricity.

“UNSW holds a record for a solar module that has four cells within the stack. It’s 40.6 per cent efficient, so you’ve got quite a margin there,” Green said.

However, an inexpensive manufacturing process for stacked cells is yet to be developed.

The Queen Elizabeth Prize winners — Andrew Blakers, Martin Green, Jianhua Zhao and Aihua Wang — outside the Royal Academy of Engineering in London © Jason Alden

Green and fellow laureates, Andrew Blakers, Aihua Wang and Jianhua Zhao, earned the Queen Elizabeth Prize for Engineering for their pioneering work on solar cells in the 1980s which made it possible to generate affordable electricity from sunlight.

Green and his colleagues published their original findings without patent protection, “encouraging further developments within the field and driving down the cost of production to the benefit of wider society,” according to the judges of the £500,000 QE prize.

“We thought commercial use of the technology would be far in the future — and that turned out to be quite an accurate assessment,” explained Green.

Wang and Zhao, a married couple who arrived from China to carry out photovoltaic research at UNSW, returned to their native country in 2006 where they founded China Sunergy, now known as CSun. The company played a leading role in building the solar cell industry in China, which now accounts for 80 per cent of global output. Blakers now works on photovoltaics at Australian National University.

“We are in the process of global energy transition with Perc and solar power in the front seat,” said Lord John Browne, former BP chief executive who chairs the QE Prize Foundation. “We are just beginning to see the impact of solar which still accounts for only 4 per cent of worldwide electricity generation. It is building momentum, particularly in the US where solar has lagged behind wind, and in a decade it should have reached 20 per cent.”

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