Scientists at UNSW are calling for stricter UV testing protocols as they uncover unexpected vulnerabilities in TOPCon cells. Their research reveals that up to one-fifth of solar PV modules degrade 1.5 times faster than average, and thicker aluminum oxide layers offer superior protection against UV-induced degradation. This discovery has significant implications for Australia's solar market, where harsh environmental conditions create the very multi-stressor scenarios that current testing protocols fail to adequately capture.
Professor Bram Hoex and Dr. Fiacre Rougieux from UNSW's School of Photovoltaic and Renewable Energy Engineering identified manufacturing defects and inadequate testing protocols as primary causes of premature module failures. Some systems may lose 45% of output by the 25-year mark or reach end-of-life in just 11 years. Multi-stressor testing is crucial, as current IEC 61215 protocols miss combinations leading to extreme degradation outcomes.
The researchers recommend manufacturers introduce multi-stressor qualification and screening that better reflects real field conditions, combining heat, humidity, voltage bias, and mechanical load simultaneously. Professor Hoex advocates for dramatic increases in UV exposure testing, moving beyond the commonly used 15kWh to 120kWh or higher, in line with updated international standards.
The research builds on previous findings demonstrating that thicker aluminum oxide layers are the dominant parameter limiting TOPCon UVID degradation. However, Hoex cautions against prescriptive thickness standards, noting that multiple mitigation strategies exist beyond simply increasing aluminum oxide thickness.
Advanced solar cell technologies, including TOPCon and heterojunction (HJT) modules, face inherent vulnerabilities as they approach theoretical performance limits. As silicon solar cells approach their theoretical performance limit, they become far more vulnerable to degradation. This challenge is compounded by the fact that advanced cell designs can suffer disproportionately from the same atomic-scale damage.
The research findings have direct implications for solar project financing and warranty structures, particularly as Australia's National Electricity Market continues to expand renewable energy capacity. Current financial models fail to account for the reality of accelerated degradation in a meaningful fraction of modules. The researchers recommend that financiers allow for a meaningful fraction of modules that fail early or degrade much faster and test whether the project can still repay the debt in those bad cases.
UNSW is developing independent testing protocols that provide more realistic assessments of long-term performance, working with partners to secure funding for both research and commercial deployment of enhanced testing methodologies. The research team's recommendations for manufacturers focus on process improvements rather than prescriptive material specifications, emphasizing stronger independent testing of randomly selected products from manufacturing lines.
