JoNova
Engineers really don’t like phrases like “right skewed degradation with a long fat tail”But new data suggests that’s exactly what’s is happening in the global solar fleet, and it’s bad news for insurers, installers, and grid planners.
One of the largest and longest studies ever done has looked at 11,000 solar panels around the world and found the same mysterious bump in unexpected failures. Surprisingly it didn’t matter whether the panels were installed in hot, cold or humid environments, the unexpected failures were still there. This suggests the higher failure rate is a systemic problem, not just something that afflicts those installed, say, in humid areas, or in the desert.
UNSW study finds up to 20% of solar panels degrade far faster than expected
By Casey McGuire Electrical Connection
Lead author Yang Tang says this has serious implications for system longevity: “Most solar systems are designed to last around 25 years, based on their warranty period.”
“But at least one in five systems degrade much faster than the typical rate and roughly one in 12 degrade twice as fast. This means some systems could lose about 45% of their output by the 25-year mark or reach the end of their useful life in as little as 11 years.”
From the Press Release:
This long tail is more than a statistical oddity. It especially poses a large financial risk for solar farms, where hundreds of thousands of panels are installed, since the data indicates there is a hidden cost associated with samples that do not perform as well or for as long as they should.
Importantly, it has also been shown that the extreme degradation observed in these panels is not related to the climatic conditions they are exposed to – ruling out the possibility that the data was being skewed by samples placed in extreme environmental locations such as very hot deserts.
Across the whole global fleet, the system performance degrades at 0.9% per year. The graph below plots the degradation rate of the energy produced from each panel. A few lemons are declining at 2, 3, or 4% annually. But the surprise is a big fat bump in panels degrading at 1.3% – 1.8% per year. That bump means that a lot more panels might fail within the warrantee period and need replacing. Maintenance costs and insurance bills will have been calculated on a normal curve, so this is an ominous sign that quite a lot of panels will not make it to the 25 year expected lifespan, and they won’t be producing as many kilowatts as expected either. So maintenance costs are going to be higher than expected. Electricity costs will be more, and to get rid of “the bump” will raise the prices of new panel designs. Someone will have to improve testing and throw away more dud panels before they leave the factory, or they will have to increase the safety margins on components.
Given that hardly any solar plants are 25 years old, we don’t know how the degradation curve will evolve over time. It’s possible these early unexpected failures might grow into a fatter longer tail as the solar fleet ages.
More:
https://joannenova.com.au/2026/02/solar-photovoltaics-degrading-faster-than-expected-8-may-only-last-11-years/
