News release

From: The University of New South Wales

Father of modern solar approaches the next frontier

Out on a patch of land near Sydney’s northern beaches, a new generation of solar panels are sitting out in the salt air, heat, humidity and rain. They are facing the harsh tests of nature and time. And if they fail, that could be quite useful.

For UNSW Sydney’s Scientia Professor Martin Green – who is often described as the father of modern photovoltaics – the future of solar power now depends not on an efficiency world record but on whether the next generation of solar cells can survive outside the lab.

Prof. Green has spent more than five decades helping solar power become a cheap source of electricity, with the technology he developed today underpinning 90% of the world's solar technology.

Now, he is helping establish an independent field-testing facility at UNSW’s Water Research Laboratory in Manly Vale, where the newest solar tech – perovskite solar modules – will be subjected to durability testing under real-world conditions.

Green says while these modules are already on the market, the expectation is that failed modules can simply be replaced as production scales and costs continue to fall.

“Silicon modules are routinely sold with warranties of 25 to 40 years,” Prof. Green says.

“While the perovskite modules offer similar warranties, the likelihood of a module surviving for that long is very small.”

Perovskites are a class of crystalline materials that can be stacked on top of silicon solar cells to harvest more sunlight and push solar performance further – the next generation of solar technology.

The new technology performs impressively in lab but is yet to survive for decades in the real world.

In the latest international solar cell efficiency tables – published last week in Joule –  Prof. Green records a large-area silicon cell reaching 28.1% efficiency and a tiny perovskite cell – not a full-size commercial module – reaching 28.0%. This is the first time the best single-junction perovskite result has effectively matched the highest silicon result.

The same report includes a 35.2% efficiency result for a perovskite-on-silicon tandem cell.

In a solar cell, a few percentage points make a massive difference. Higher efficiency means more electricity from the same rooftop, less land required for solar farms, with lower installation and infrastructure costs across entire energy systems.

The report’s latest numbers suggest solar is edging towards another technological shift – if the cells can last.

“Silicon, the workhorse of the global solar revolution, is now very efficient, but increasingly close to its limits,” Prof. Green says.

“And anyone who’s made a perovskite cell knows how unstable they are.”

Testing the future

Can perovskites make the same leap silicon did from promising technology to reliable infrastructure?

This question is what shapes the field-testing facility.

Prof. Green says perovskite-on-silicon tandem cells are the most likely large-scale commercial pathway for next-gen solar technology.

“All the silicon manufacturers have their own perovskite-on-silicon programs,” he says.

When his group first began setting records with silicon cells, he insisted any claims be certified by recognised testing laboratories.

“If you’re claiming a record, you’ve got to have it independently certified,” he says.

That insistence on verification became a foundation of the modern solar industry. And it persists today through the independent field-testing facility Prof. Green is helping establish alongside his former student, UNSW’s Dr Jessica Jiang.

The facility will be able to install up to 160 modules, catering to all manufacturers and generations of products.

Many perovskite manufacturers are part of China’s rapidly expanding solar industry – and Prof. Green’s former students.

One of the largest perovskite manufacturers, Microquanta, was started by two former students.

Another former student is the founder of Suntech, Dr Zhengrong Shi, whose commercialisation of modern solar technology helped catalyse China’s rise as a global solar manufacturing powerhouse.

“Jessica has really good contacts within the Chinese industry, largely because they’re former students who now have important jobs in the industry,” Prof. Green says.

“She can WeChat them and the next day they’ll put a module in the mail.”

By comparing modules from different companies, the UNSW team hopes to identify which failure mechanisms are widespread and which are specific to individual designs.

“We’ll be able to provide an authoritative opinion about just how good the commercial ones are,” Prof. Green says.

“Once they fail in the field, we’ll find out why and provide that information back to the manufacturer,” he says.

“We really think we can push things along a bit.”

From oil shocks to world records

When Prof. Green began working on solar cells in the early 1970s, photovoltaics were niche and expensive.

The cost didn’t matter so much in the space industry, which had been using solar cells in spacecraft since the late 1950s. But back down on Earth, they were too expensive to be taken seriously as an everyday power source.

Then, the oil crises of that decade forced governments to think seriously about energy security – particularly after embargoes disrupted fuel supplies across the Western world.

“There were queues at service stations, cars running out of petrol – in a world suddenly worried about oil dependence,” Prof. Green says.

He says solar then “got a guernsey” in efforts to reduce dependence on imported oil.

“They had to bring the cost down by a factor of a thousand or more from what they cost to put on satellites,” he says.

At the time, nuclear power dominated much of the energy imagination. Prof. Green says one nuclear advocate dismissed solar as likely to have “all the impact of a flea on an elephant’s back”.

But, he says, the political and scientific mood began to shift. A US program helped set the international tone. Japan launched its Sunshine Project. Europe followed with its own efforts. And Australia began its own solar program in 1978.

Prof. Green joined UNSW as an academic in 1974 and set up a solar research group soon after. By the early 1980s, his group was known internationally.

In 1983, he and his team invented Passivated Emitter and Rear Cell (PERC) technology. This led to them then producing the world’s first officially confirmed 18% efficient silicon solar cell, beating the previous record of 16.5%.

That result pushed UNSW to the front of a field that included major US companies, NASA-linked programs, Japanese laboratories and other universities – with Prof. Green’s research team holding the record for silicon solar cell efficiency for much of the past four decades.

And last year, solar generated more electricity worldwide than nuclear for the first time, with the gap rapidly increasing.

Faster than expected

The role of solar today has expanded to being a resource that combats climate change. But its appeal still sits with its 1970s roots – as a technology tied to energy security, economic resilience and independence from volatile fossil fuel markets.

In Australia, solar already supplies a substantial share of electricity. Prof. Green says the contribution from solar is now doubling every few years and could become the dominant source of electricity far sooner than many expect.

“We’ll be generating most of our electricity from solar by about 2032,” he says.

He says conservative energy forecasts have repeatedly underestimated renewable deployment. Even projections that now speak positively about renewables, he says, often still assume they will play a smaller role than growth trends suggest.

For someone who has spent more than five decades not just watching, but helping solar outperform expectations, he is reluctant to underestimate what comes next.

“Things have exceeded even my projections as an optimistic person in the field.”