A groundbreaking study by UNSW scientists has revealed a critical vulnerability in solar module testing protocols, sparking a call for urgent action to enhance industry standards. The research, led by Professor Bram Hoex and Dr Fiacre Rougieux from UNSW's School of Photovoltaic and Renewable Energy Engineering, has uncovered a shocking reality: up to one-fifth of solar PV modules are degrading at an alarming rate, up to 1.5 times faster than average!
But here's where it gets controversial... the study also found that thicker aluminium oxide layers provide superior protection against UV-induced degradation in TOPCon cells. This has significant implications for the solar industry and raises questions about current testing practices.
Professor Hoex and Dr Rougieux highlight the primary contributors to premature module failures as manufacturing defects and inadequate testing protocols. They warn that some systems could lose up to 45% of their output by the 25-year mark, or even reach their end-of-life in just 11 years!
The researchers emphasize the need for multi-stressor testing, which they believe is currently lacking in industry standards. Dr Rougieux explains, "What we show is that fast-degrading modules are more likely to have multiple degradation modes activated. IEC 61215 testing, which is the leading international standard, primarily consists of separate single-stressor tests run in defined sequences. This approach may miss the combinations that create extreme degradation outcomes."
IEC 61215 ensures PV modules can endure long-term outdoor operation by testing environmental durability, including UV light exposure, humidity, and thermal cycling, as well as mechanical strength. However, the research team argues that these tests fall short of capturing the real-world conditions that solar modules face, especially in harsh environments like Australia.
Professor Hoex advocates for a dramatic increase in UV exposure testing, suggesting manufacturers move beyond the commonly used 15kWh to 120kWh or higher, in line with updated international standards. He states, "I strongly encourage manufacturers to test their solar cells under much higher ultraviolet exposure. This allows them to make informed decisions about acceptable degradation levels."
The study builds on previous findings, demonstrating that while thicker aluminium oxide layers help reduce UV-induced degradation, there are multiple mitigation strategies beyond this. Hoex cautions against imposing a fixed standard for aluminium oxide thickness, as there are likely unknown ways to improve a module's resistance to UV damage.
The research also reveals a fundamental challenge for next-generation solar cell technologies like TOPCon and heterojunction (HJT) modules. As these cells approach theoretical performance limits, they become increasingly vulnerable to degradation. In record-setting TOPCon cells, minor UV-induced damage can lead to voltage losses exceeding 20 millivolts, highlighting the fine line between peak performance and reliability.
And this is the part most people miss... the financial implications of these findings. Rougieux notes that current financial models fail to account for accelerated degradation in a significant fraction of modules. He suggests financiers should allow for early failures or faster degradation rates and test if projects can still repay debts in these scenarios. The researchers recommend enhanced independent testing beyond IEC standards, with organizations like KIWA PVEL demonstrating the potential for more comprehensive approaches.
UNSW is developing independent testing protocols to provide realistic assessments of long-term performance. The study's recommendations for manufacturers focus on process improvements rather than material specifications, emphasizing the need for stronger independent testing of randomly selected products from manufacturing lines.
As Australia's solar industry expands, these research findings offer critical insights to ensure long-term system reliability and financial viability. The study's revelations challenge the industry to adopt more rigorous testing protocols, highlighting the importance of comprehensive testing to capture real-world degradation scenarios and drive innovation in mitigation strategies.
What are your thoughts on these findings? Do you think the solar industry is doing enough to address these vulnerabilities? We'd love to hear your opinions in the comments!
