UNSW solar discovery sets new silicon efficiency benchmark

The solar industry has long been focused on bringing down the cost of silicon, but have been stuck on how to do this without creating compromising its quality and thus reducing panel efficiency?

Now, a team of Australian solar engineers from the UNSW say they have found a way to dramatically improve the quality of low-grade silicon, that would both reduce the cost of solar panels and boost their efficiency.

The new technique, patented by UNSW researchers earlier this year, is expected to produce efficiencies between 21-23 per cent, up from the current maximum of around 19 per cent for standard commercial silicon cells.

The key is in the discovery of a mechanism to control hydrogen atoms so they can better correct deficiencies in silicon – by far the most expensive component used in the manufacture of solar cells.

The use of hydrogen atoms to help correct defects in the atomic structure of silicon is not a new concept, but until now, scientists have had limited success in controlling the hydrogen to maximise its benefits – or even in understanding why this happens.

“Our research team at UNSW has worked out how to control the charge state of hydrogen atoms in silicon,” said Scientia Professor Stuart Wenham from the School of Photovoltaics and Renewable Energy Engineering at UNSW. “This process will allow lower-quality silicon to outperform solar cells made from better-quality materials.”

“By using lower-quality silicon to achieve higher efficiencies, we can enable significant cost reductions,” Wenham said.

“We have seen a 10,000 times improvement in the mobility of the hydrogen and can control the hydrogen so it chemically bonds to things like defects and contaminants, making these inactive.”

The UNSW team currently has eight industry partners interested in commercialising the technology, and is also working with manufacturing equipment companies to implement the new capabilities.

The project, which has been generously supported by the federal government’s Australian Renewable Energy Agency, is expected to be completed in 2016.

UNSW still holds the world-record for silicon cell efficiency at 25 per cent, and last week, Scientia Professor and solar pioneer Martin Green, was elected into the Fellowship of the United Kingdom’s prestigious Royal Society.