A new report from the International Energy Agency Photovoltaic Power Systems Programme (IEA PVPS) under Task 13 looks into innovations in solar PV technology that address known degradation challenges. But as new failure modes in emerging materials and designs come up, report writers stress on improved testing methods to ensure long-term reliability.
This report specifically examines the impact of degradation and failure modes in new solar cell technologies, namely TOPCon and silicon heterojunction (SHJ). For these technologies, the challenge of cell cracking has mostly been overcome by the innovation of multi-wire technology, while the issues related to LID/LeTID have been solved with the switching of boron to gallium-doped wafers.
Potential-induced degradation (PID) continues to pose a challenge, but tests show that its impact can be significantly lowered through UV exposure, especially for TOPCon cells. For SHJ, however, a new potential PID degradation mechanism has been identified although no such PID-affected modules are found in the field as yet, add the report writers.
“To assess the irradiation impact on real installations, the upcoming PID standard IEC TS 62804-1 (2025) offers a combined potential and light test procedure,” state the writers.
The standard IEC 61215 series of tests are not enough to detect the reliability issues related to encapsulation, glass durability and even junction box failures since these are mostly designed to assess the electrical performance of the modules, and not on the stability aspects of polymer materials. Thin glass modules with a thickness ≤ 2mm in dual glass configuration sometimes lead to unpredictable high glass breakage rates, but the standard IEC tests cannot reveal this vulnerability.
Even when it comes to junction boxes, the electrical contacts are at times found not soldered correctly. This can lead to fires and power losses in entire module strings.
Even beyond the mainstream TOPCon and SHJ technologies, the IEA PVPS report also looks into the reliability of metal halide perovskite (MHP) modules. Their commercial use is still not widespread, yet they are susceptible to temperature stability and ion migration. Protective encapsulation can mitigate effects related to UV radiation, moisture and oxygen to improve their stability.
“To produce reliable PV modules, all degradation pathways must be understood and mitigated in one solution. There are currently no comprehensive solutions in the literature to address the multiple reliability issues of PSCs,” reads the report.
While technological advances have addressed some degradation issues, new materials and designs demand improved testing, manufacturing controls, and research to enhance PV module reliability and safety. Report writers recommend reviewing past reports on degradation modes and conducting accelerated testing calling it crucial to minimize failures in large PV systems.
The report is titled Degradation and Failure Modes in New Photovoltaic Cell and Module Technologies. It is available on IEA PVPS website.
This report is accompanied by Photovoltaic Failure Fact Sheets (PVFS) 2025, which IEA PVPS says offers practical and field-oriented information crucial for planners, installers, investors, inspectors, consultants, and insurance companies in the solar energy sector.
