A UNSW study on solar module degradation assessed information from nearly 11,000 solar panel samples globally
They found that about 20% of solar panels degrade at least 1.5 times faster than the typical rate of around 0.9% per year; roughly one in 12 degrade twice as fast
Usually designed for a 25-year lifetime, some panels may effectively last only around 11 years, losing up to 45% of output by the 25-year mark
The study attributes extreme degradation mainly to manufacturing defects, interconnected component failures, and minor flaws that worsen over time
A new University of New South Wales (UNSW) study found that about 1 in 5 solar panels degrade much faster than expected, with some lasting only about half of their anticipated lifetime. Designed to last around 25 years as per the warranty promised, such panels could work only for 11 years, losing about 45% of their output by the 25-year mark, the researchers claim.
The findings follow an assessment of information from nearly 11,000 different panel samples globally, raising concerns about long-term performance and reliability in parts of the global solar fleet.
“For the entire dataset, we observed that system performance typically declines by around 0.9% per year. However, our findings show extreme degradation rates in some of the systems,” said one of the team members and authors of the study, Yang Tang. “At least one in five systems degrade at least 1.5 times faster than this typical rate, and roughly one in 12 degrade twice as fast.”
According to the researchers, while many panels degrade smoothly and predictably, when plotted on a graph, the results show a ‘long tail’ of sampled that fail a lot more rapidly than should be expected.
This long tail in the probability distribution of the performance data is more than a ‘statistical oddity’. They stress that this creates a serious financial risk for large-scale solar farms, as these come with hidden costs.
The study rules out climatic conditions as the cause of the extreme degradation that the panels are exposed to. Rather, the findings identify 3 major reasons for the presence of panels in the long tail. These are:
Interconnected failures or failure of one component impacting the performance of the rest of the system in a domino effect. For instance, failure of the backsheet can cause moisture to seep in, leading to problems like corrosion, etc.
Rapid failure or infant mortality is a phenomenon that often occurs with newly installed modules. However, when some modules with critical manufacturing defects or material flaws that go unnoticed during quality control or testing are installed, they degrade faster than expected.
Minor flaws could also lead to rapid degradation; they may not cause any problems initially, but may report severe decline in performance.
“Current testing standards focus primarily on three parameters: the modules’ response to mechanical stress, extreme temperatures, and exposure to ultraviolet radiation - as well as often testing for humidity and response to a standardised amount of sunlight (AM1.5 spectrum),” explains Dr. Shukla Poddar, a co-author of the study. “But when they are actually operating in real-world conditions there are so many different factors coming into play, and those cascading failures can be very significant.”
Earlier, the Kiwa PVEL 2025 Scorecard also highlighted a worrying trend of increased testing failure among modules. It found 83% of tested module manufacturers had at least 1 test failure, the highest rate ever recorded (see Test Failures Surge In Kiwa PVEL’s 2025 Module Reliability Scorecard).
The recent TaiyangNews Reliable PV Module Design 2025 Conference featured speakers and experts in the field, who stressed module reliability, especially as new technologies are being adopted faster than ever in the face of cost pressures and intense competition. They also stressed the need for module-level evaluations to evolve (see Rapid Solar PV Module Evolution Puts Reliability In Spotlight).
UNSW team says its findings are intended to inform testing authorities about real-world degradation patterns across climates, encouraging improved and combined stress tests that better reflect outdoor operating conditions.
Its findings highlight the need to improve quality standards and testing methods for solar panels, it added.
The complete study titled Understanding and Reducing the Risk of Extreme Photovoltaic Degradation is available on the IEEE Xplore website.
