Father of modern solar approaches the next frontier

After helping solar power evolve from a niche technology into one of the world’s cheapest sources of electricity, UNSW’s Professor Martin Green is preparing for the next era as silicon cells near their limits.

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. They may fail quickly – but 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.”