The independent American laboratory Renewable Energy Test Center (RETC) released its annual PV Module Index Report 2025, traditionally considered one of the most influential industry documents assessing the real-world reliability, performance, and quality of solar modules.
The 2025 results were particularly revealing – RETC documented both significant achievements by leading manufacturers and a number of new technical challenges for the industry.
Who became the leader of 2025: the highest rating "Overall Highest Achiever"
Based on the results of comprehensive testing, 12 manufacturers received the report’s top award—Overall Highest Achiever 2025. These included:
- LONGi
- JinkoSolar
- Trina Solar
- JA Solar
- DASolar
- DMEGC
- Runergy
- VSUN Solar
- Waaree
- SolarSpace
- Astronergy
- Yingli
This award is given to companies that demonstrate high results in all key test groups: reliability, productivity and quality of production processes.
Key Trends and Conclusions RETC 2025
- Increasing number of defects in long-term reliability tests
The report noted that, compared to previous years, the number of modules that perform poorly in tests such as:
- Thermal cycling (TC)
- Humidity + heat (DH)
- Potentially induced degradation (PID)
- Mechanical stress
RETC specifically highlights the increase in problems associated with glass and module frames, particularly under the influence of wind and mechanical loads.
- Ultraviolet degradation (UVID) is a major new challenge for the market
RETC in 2025 focused on the results of accelerated UV exposure tests.
The report recorded:
- more than 5% degradation after 110 hours of accelerated UV testing for a large number of tested modules;
- in the worst cases, degradation exceeded 12%.
Moreover, the influence of UV deformation is evident not only in TOPCon modules, but also in products manufactured using PERC and HJT technologies.
- N-type TOPCon – both a trend and a risk zone
While most manufacturers are actively switching to n-type TOPCon, RETC warns: this technology does not automatically guarantee better durability.
Therefore, the report specifically highlights those n-type brands that demonstrated high stability. Specifically, LONGi and Trina Solar strengthened their positions thanks to improved reliability results.
Comments from manufacturers
1
LONGI
said that achieving High Achiever status for the seventh consecutive year reflects the consistent quality of their modules.
2
JinkoSolar
sixth year among the leaders. Noted for “the best balance of performance and durability.”
3
VSUN Solar
for the second year in a row, it has received the highest overall award, confirming the company’s gradual strengthening in the premium segment.
What do the RETC 2025 results mean for the industry?
Competition is growing as twelve brands received high ratings.
N-type TOPCon is not a panacea – what matters is the actual quality of production, not just the technology.
Long-term reliability issues are becoming more pressing due to the increasing number of defects in new module models.
UV degradation will be one of the key metrics in the coming years.
