Saturday, 11 June 2016

World-first plant to rejuvenate solar cells

The NTU-UNSW facility could prove a major money-saver for the industry
By Carolyn Khew, The Straits Times, 10 Jun 2016

A new facility, to be set up by year-end, could save the solar cell industry millions of dollars.

The US$2 million (S$2.7 million) plant, to be built at Nanyang Technological University (NTU), will be the first in the world that can rejuvenate degraded solar cells and treat them - and new cells - so that they do not degrade throughout their lifespan.

Solar cells lose their efficiency and generate less electricity over time when exposed to sunlight and heat. It is estimated that efficiency loss could be 20 per cent in a cell's 25-year lifespan. This is known as light-induced degradation and has plagued the industry for decades.

However, about six years ago, a team - which included Professor Stuart Wenham and Associate Professor Chong Chee Mun from the University of New South Wales (UNSW) in Sydney - came up with a method to reverse and stop light degradation.

They found a way to control the hydrogen atoms found in solar cells, which are made of silicon. This control enabled them to make the hydrogen atoms bond chemically with the degraded parts of the cell and thus rejuvenate them.

The hydrogen treatment also works on new cells to prevent degradation.

The whole process takes only about eight seconds, said Prof Wenham, who is the director of the UNSW's Photovoltaics Centre of Excellence. He was in Singapore recently to discuss plans for the new hydrogenation facility.

Prof Chong, director, industry collaboration of the UNSW's Photovoltaics Centre of Excellence, added: "With the technology, we are reverting the efficiency of the solar cell to what it was at the start, or even better than at the start because we have gotten rid of the light-induced degradation and other defects in the silicon.

"And these cells, more importantly, will not degrade again."

The professors decided to team up with Adjunct Associate Professor Matthew Tan from NTU to take the technology to Singapore to commercialise it. Their plant is a joint collaboration between solar technology development firm CEC Energy, NTU and UNSW.

Once it is set up, solar-cell makers can send new cells to "degrade-proof" them as well as send in old cells for repair.

In the long run, there are plans to make the technology more portable so that solar energy users all over the world can have their cells repaired without dismantling them.

Plans to develop the NTU facility come even as Singapore aims to use solar energy for 5 per cent of the projected peak electricity demand here - about 350MWp, where "p" stands for "peak" - by 2020.

It is estimated that renewable energy could contribute up to 8 per cent of Singapore's peak electricity demand by 2030, according to the National Climate Change Secretariat's website.

Professor Armin Aberle, the chief executive of the Solar Energy Research Institute of Singapore, said that light-induced degradation causes solar panels to produce less electricity with power losses amounting to about 5 per cent.

For a power plant operator in Singapore with a peak power output of one megawatt, this corresponds to a loss in revenues of about $10,000 a year, or more than $250,000 over the plant's 25-year lifespan.

"This significantly affects the profitability of the plant and thus should not be neglected," said Prof Aberle.

"If the curing method offered by this new facility in Singapore is of sufficiently low cost and long-term stable, then there is a clear business case."

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