If you look up at any one of the three million roofs in Australia with solar panels that have been recently installed, you’re almost certainly looking at the work of Sydney-based engineer, Professor Martin Green. It’s fair to say that, without his contribution, the solar-energy industry as we know it would not exist.
The solar cell invented by Green in 1983 now accounts for more than 90% of worldwide solar-cell production and soon will be responsible for generating half of the world’s solar power. If growth continues, it’s projected to reduce greenhouse-gas emission by 5% each year by the late-2020s.
The revolutionary PERC (passivated emitter and rear contact) cell developed by Green and his team was a huge leap in solar-cell efficiency, hitting 23% in 1989 – a feat that seemed impossible at the time. Photovoltaic technology had been in stagnation for the decade prior to Green’s work, with the most efficient solar cells converting 17% of sunlight into electricity.
The success of the PERC cell, which perfected the silicon-crystal surfaces to reduce electronic losses, was during a period of intense global competition to further improve solar-cell efficiency. Green’s team have held the record for silicon-cell efficiency for 30 of the past 38 years, most recently through continued innovations to PERC cell technology.
In recent years, it’s become more difficult to compete with the kinds of resources that commercial manufacturers can dedicate to improving solar-cell efficiency, says Green. The efficiency record is now held by the Japanese company, Kaneka, at 26.7%.
“It’s at a completely different scale now,” Green told The Brilliant. “Manufacturers can employ 100 people in their research team and they’re pumping out thousands of research cells a day. Doing this is really important to them. It’s their bread and butter. They need to keep ahead of their competitors.”
PERC cell technology is still highly competitive. “It’s a little bit too hard for other cell approaches to catch up,” says Green. “Everyone says ‘We can do better – in five years, we’re going to get the cost down to this or that.’ But in five years, PERC has moved along a similar trajectory, so they never catch up.”
With the head-start provided by the PERC cell, Green has had the advantage of thinking steps ahead of his competitors. “I try to think of what the next big problem’s going to be, whereas these companies are working on the here and now,” he says. “I’m trying to anticipate what’s going to happen a bit down the track.”
Green’s team hold the world record for converting sunlight to energy, 40.6%, which is double the standard commercial rate. “No one’s come close to that,” he says.
If commercial cells are raised to similar efficiency levels, this will halve the number of solar panels for the same output, says Green. “To make cells twice as efficient, we need other cells made from a new type of material that we can stack on top of the silicon cells,” says Green.
Finding that material is proving a challenge. It needs to be abundant (and therefore cheap), non-toxic, stable, and still produce cells that are highly efficient.
“We’ve got one that ticks three of those boxes, but it’s only at 11% efficiency and we’ve got to get it up to 20%,” says Green.
Next-gen sun kings
What drives Green to keep pushing his research further is the feeling that he can make a difference. One of his best memories is seeing a huge field of solar modules in 1992, which multinational oil and gas company BP had licenced to produce from his research.
“Just seeing the size of it,” says Green, “all this is the result of the work we did in the lab, making those tiny cells, and here we’ve got this big system. That was really a very nice moment.”
His research, and that of his many students, has helped to transform the solar industry from what he calls a boutique industry, to a global, commercially viable one. “This has led to solar being the cheapest source of electricity generation, right at the time when the world has started getting serious about climate change,” he says.
After graduating from the University of Queensland, Green completed a PhD in engineering physics at Canada’s McMaster University, before landing at the University of New South Wales (UNSW) in 1974, where he’s been ever since.
It was at UNSW where he grew his world-class research group, supporting the next generation of solar scientists, and launching the careers of several of his students – the most well-known being Zhengrong Shi, dubbed by the media as the ‘Sun King’.
Shi founded Suntech Power, China’s first solar cell producer, in 2001, and grew it into a multi-billion-dollar company, which at one point was the world’s biggest manufacturer of solar cells.
Suntech was the first private Chinese company to list on the New York Stock Exchange, Green says, in what was also the biggest technology float of 2005 worldwide. “I never thought I’d be helping someone ring the bell on the biggest technology float of the year,” says Green.
It was a hard slog for Shi, as China had only just relaxed strict rules about private companies, and he was essentially setting up a new industry.
“He was successful, despite the odds; there was just no infrastructure in China,” Green says. “All the stuff he needed to make the cells had to be imported —he had to buy the glass from Sydney and import it into China. It sounds a bit weird now, when China’s sort of swamping the world with solar glass, but that’s the way it was 20 years ago.”
That success spurred on a lot of Green’s group.
“Some of them founded other companies and they quickly got big,” says Green. “Zhengrong was showing how money could be made from solar, so they were able to get funding from US exchanges and compete with him.”
Did Australia scupper the solar opportunity?
It’s been argued that Australia squandered its chance of owning the solar-energy industry, given how much natural sunlight and world-leading research we have. But Green disagrees.
Keeping the manufacturing in Australia would never have tipped the industry into a globally viable one, he says. Going to China was pivotal.
The only reason that solar cells are cheap now is that Zhengrong went to China and did that. It was simply cheaper to produce in China and at the time American investors were hungry for Chinese stocks. That really kick-started the whole solar industry in China,” Green says.
But Australia is well-positioned on the global solar-energy scale in being able to use the solar modules to generate electricity from them more cheaply than most other developed nations.
“That’s a real advantage,” says Green. “We have plenty of sunshine. We have plenty of industries that could exploit the energy they generate, and we have more solar panels installed per capita than anywhere else in the world.”
Green predicts that solar energy’s 10% slice of Australia’s electricity use will rise to 50-60% over the next decade.
It’s ironic is that Australia may have more sunshine converted to energy in peak generation times than we know what to do with – a problem that Green is also keen to see addressed.
“We’re going to have plenty of solar panels installed over the coming decade and we’re going to have a lot of spare electricity around midday as a consequence of that,” he says.
“If the market gets flooded with electricity, the prices drop to negative value, so finding something to do with that electricity is really important. I think that’s the type of thing Australia should be thinking about and concentrating on.”
Transmitting that electricity is important, he says.
“What you really need to do is pipe the electricity efficiently around the country,” he says.
We’ve got very good wind in Australia, as well as solar, so we’re blessed with both. And they’re very complementary because the wind generally blows in winter and at night-time and the solar does the opposite. We should embrace the opportunity that our natural advantages in solar gave us.”
Article by Kylie Ahern
Photo Credit: Anna Kucera
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