UNSW–ACAP team guides industry in prevention of corrosion in TOPCon solar cells
- 5 days ago
- 4 min read
In 2025, researchers led by Professor Bram Hoex (UNSW) tackled one of the most serious and least visible threats to next-generation solar technology: corrosion and chemical degradation in high-efficiency silicon solar cells. As the global industry rapidly shifts to tunnel oxide passivated contact (TOPCon) and heterojunction (HJT) technologies, understanding and controlling these degradation pathways has become essential to ensuring long-term performance, bankability, and investor confidence.
Supported by ACAP-funded infrastructure and collaborative projects, this research addressed corrosion as a system-level challenge – spanning cell architecture, materials chemistry, manufacturing processes, handling, and module assembly. Small, often invisible changes at any stage can quietly undermine the lifetime of high-efficiency solar modules once deployed in the field.
“TOPCon presents an exciting leap in efficiency, but to ensure its long-term success, we must understand its unique sensitivities to environmental stresses and manufacturing choices,” said Professor Bram Hoex, who is also Technical Lead for ACAP’s Device to Module research program package.
“The manufacturing process is evolving rapidly, and small adjustments can either strengthen or weaken long-term stability. Identifying these vulnerabilities is essential for designing solar modules that perform reliably in Australia’s climate, and at scale globally.”
Working closely with industry partners, including Canadian Solar, Jolywood, and Tindo Solar, the Hoex Group combined fundamental degradation science with solutions implementable in modern production lines.
Australia’s only solar module manufacturer, Tindo Solar produces panels that are designed to withstand intense sunlight, coastal salt spray, wide temperature fluctuations, high humidity and hailstorms – conditions that can otherwise lead to delamination, corrosion, condensation and long-term power loss.
“Tindo and UNSW are optimising TOPCon technology to deliver high power output across diverse climatic conditions,” said Richard Petterson, CEO of Tindo Solar.
“Tindo has strong in-house design and engineering capability, but partnering with a leading research organisation such as UNSW is critical. It’s this blend of industry and research that will deliver the next generation of solar technology.”
A laser-assisted firing process for industrial TOPCon cells delivered an efficiency gain of ~0.6% (absolute) while improving resistance to corrosion and damp-heat exposure1,2. By reducing losses at the metal–silicon interface, the process enables manufacturers to use lower-aluminium pastes, cutting costs and improving production yield.
The team also showed that copper plating of cell contacts can dramatically slow corrosion. In accelerated damp-heat tests, conventional TOPCon cells rapidly lost performance, while copper-plated cells retained the majority of their efficiency3. This approach reduces silver use, improving sustainability while maintaining electrical performance.
Beyond device engineering, ACAP researchers uncovered how trace contamination from gloves, packaging, or handling equipment can drive significant power losses under humid conditions4,5.
“Reliability is as much about process discipline as it is about materials,” said Dr Chandany Sen (UNSW), lead author on several of the studies.
“Small choices in handling or assembly can have large consequences years later.”
Complementary studies demonstrated that certain soldering fluxes can chemically attack sensitive layers in advanced cells, particularly HJT devices6, highlighting risks even in sealed modules.
Dr Xinyuan Wu (UNSW), a lead author on several of the studies, noted: “By identifying and understanding how corrosion initiates at contacts, we can design protection strategies that are scalable and immediately relevant to manufacturers.”
Their work has attracted substantial industry and media attention, including coverage in the international and Australian editions of PV‑Magazine. Results were presented at major international and regional forums, including the European Photovoltaic Solar Energy Conference (EU PVSEC 2025) and the Asia-Pacific Solar Research Conference (APSRC 2025), as well as invited industry-focused seminars and webinars.
By linking fundamental science with scalable solutions – from laser-assisted firing to copper-plated contacts and atomic layer deposition barriers (ALD) 4 – this research provides practical, bankable strategies for producing TOPCon and HJT modules that are more reliable, lower cost, and better suited to diverse climates. The Hoex team’s work sets a benchmark for comprehensive, system-level PV reliability research, reinforcing Australia’s position as a global leader in solar materials and manufacturing science.
“Addressing corrosion and degradation isn’t just about individual cells, it’s about the entire production and deployment system. Our work links fundamental science directly to the decisions manufacturers make every day and enables more reliable solar that is built to last.” – Professor Bram Hoex
References
Wang, X., Yuan, J., Wu, X., Nie, J., Zhang, Y., Zhang, X., Yang, W., Li, F., & Hoex, B. (2025). Higher‑efficiency TOPCon solar cells in mass production enabled by laser‑assisted firing: Advanced loss analysis and near‑term efficiency potential. Progress in Photovoltaics: Research and Applications, 33(7), 771–781.
Wu, X., Wang, X., Lv, R., Song, H., Yu, Y., Sen, C., Cheng, Y., Khan, M.U., Ciesla, A., Xu, T., Zhang, G., & Hoex, B. (2025). Unveiling the degradation mechanisms in silicon heterojunction solar cells under accelerated damp‑heat testing. Solar Energy Materials and Solar Cells, 282, 113325.
Wang, X., Sen, C., Wu, X., Chang, Y.‑C., Wang, H., Khan, M.U., & Hoex, B. (2025). Alleviating contaminant‑induced degradation of TOPCon solar cells with copper plating. Solar Energy Materials and Solar Cells, 282, 113444.
Tong, H., Wu, X., Wang, X., Xu, X., Guo, M., Liao, B., Ma, S., Li, Z., & others (2025). Mitigating contaminant‑induced surface degradation in TOPCon solar cells: Mechanisms, impacts, and mitigation. Solar Energy Materials and Solar Cells, 286, 113558.
Sen, C., Wang, H., Khan, M.U., Fu, J., Wu, X., Wang, X., & Hoex, B. (2025). Hidden traces: How solar cell handling drives damp‑heat failures in HJT and TOPCon modules. Solar Energy Materials and Solar Cells, 289, 113695. https://doi.org/10.1016/j.solmat.2025.113695
Fu, J., Sen, C., Wang, H., Song, H., Lv, R., Huang, T., & Hoex, B. (2026). Assessing the impact of solder flux‑induced corrosion on TOPCon solar cells. Solar Energy Materials and Solar Cells, 294, 113890. https://doi.org/10.1016/j.solmat.2026.113890
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