Researchers at UNSW Sydney have achieved a new efficiency record for perovskite-silicon tandem solar cells, reaching 29.8% conversion efficiency in a device that uses manufacturing techniques compatible with existing solar panel production lines.

That matters because perovskite solar cells have been breaking efficiency records for years, but most designs use processes that would be prohibitively expensive to scale up. This new approach could actually make it to market.

The tandem cell design stacks a perovskite layer on top of a standard silicon solar cell. The perovskite layer absorbs blue and green light while allowing red and infrared light to pass through to the silicon layer below. This lets the cell capture more of the solar spectrum than silicon alone.

Standard silicon solar cells max out around 26-27% efficiency due to fundamental physics limitations. Tandem designs can theoretically reach 35% or higher, which translates to more power from the same roof area and lower overall system costs.

Professor Martin Green, who founded UNSW’s photovoltaic research program in the 1970s, called the result significant but cautioned against over-optimism. “We’ve seen efficiency records before that never made it to production. The question is always durability and manufacturability.”

That’s the challenge with perovskites. Early versions degraded rapidly when exposed to moisture, heat, or UV light. You can’t sell a solar panel that fails after six months.

The UNSW team addressed stability by modifying the perovskite crystal structure and adding protective layers. Their cells maintained over 95% of initial efficiency after 1,000 hours of accelerated aging tests, equivalent to roughly two years of outdoor exposure.

Accelerated testing doesn’t perfectly predict real-world performance, but it’s a necessary step toward commercialisation. Solar panels typically come with 25-year warranties, so manufacturers need high confidence in long-term reliability.

The research received support from the Australian Renewable Energy Agency (ARENA), which has invested over $100 million in advanced solar research since 2020. ARENA’s bet is that next-generation solar technology could become a significant export industry for Australia.

Several Australian companies are working to commercialise perovskite technology. Greatcell Solar, based in Queanbeyan, has been developing perovskite manufacturing processes for years. Oxford PV, though UK-based, has significant Australian research ties and aims to begin commercial production of tandem cells in 2026.

The economic case for better solar cells is straightforward. Even a few percentage points of efficiency improvement can significantly reduce the levelised cost of electricity from solar farms. That matters most for large-scale installations where land, mounting hardware, and installation labour are major costs.

For residential solar, the case is a bit different. Roof space is often the limiting factor, so higher efficiency panels let homeowners install more capacity in the same area. That’s particularly relevant in Australian cities where residential solar penetration already exceeds 30% in some suburbs.

One question is whether perovskite tandems can compete with improvements in traditional silicon cells. Silicon technology continues advancing, with several manufacturers now producing panels exceeding 23% efficiency using selective emitter designs and better anti-reflection coatings.

The UNSW research group is simultaneously working on all-perovskite tandem cells that stack two different perovskite layers instead of combining perovskite with silicon. Those could potentially reach even higher efficiencies but face greater manufacturing challenges.

Australia has a strong track record in solar research. UNSW has held the silicon solar cell efficiency record multiple times over the past four decades. That research capability hasn’t always translated to local manufacturing, though. Most solar panels installed in Australia are manufactured overseas, primarily in China.

The federal government’s solar manufacturing incentive program, announced in 2024, aims to change that by subsidising local production. Whether that succeeds depends partly on whether Australian companies can commercialise next-generation technologies like perovskites before international competitors.

For now, the UNSW result is a proof of concept. Commercial panels using this technology probably won’t hit the market until 2027 or 2028, assuming stability testing and manufacturing scale-up proceed smoothly.

But it’s another data point suggesting that solar technology still has room for significant improvement, even after decades of research and development.