The 2026 RETC module testing report reveals a concerning trend in the solar energy industry. Damp heat and Ultraviolet-Induced Degradation (UVID) are the top 'red flag' issues, with 8% of modules failing UVID tests, the second-highest rate among all test categories. This is a significant increase from the previous year, indicating a growing problem with module durability. The report highlights a concerning pattern of underperformance, with a decline in median and average scores across all testing types, suggesting a potential issue with long-term durability. VDE Americas' Beth Copanas warns that design optimization efforts, aimed at reducing manufacturing costs, may be inadvertently impacting module performance and reliability. This is particularly concerning given the industry's reliance on China-based manufacturing expertise for highly refined processes like TOPCon.
The proliferation of UVID is linked to the relocation of TOPCon manufacturing outside China, where regulations and expertise may not be as stringent. Cherif Kedir of RETC emphasizes the importance of tight control over manufacturing steps to ensure cell reliability. However, moving these processes to new locations can lead to variations in reliability, even with the same equipment and materials.
Despite these challenges, the report also highlights some positive developments. Backsheet ultraviolet durability testing achieved 100% high achievement, and light- and elevated temperature-induced degradation returned a high achiever percentage of 66%. Additionally, 13 companies received the 'overall highest achiever' status, indicating their consistent ability to produce robust modules. However, the industry's struggle with hail resistance and the increasing underperformance across all testing types remain significant concerns that need to be addressed to ensure the long-term success and reliability of solar projects.
