Revolutionary Monitoring Technique Reveals how Solar Cells Self-Repair Under Sunlight
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New insights into ultraviolet-induced degradation coudl lead to more durable and efficient solar panels, transforming testing and design standards.
Engineers at UNSW Sydney have achieved a breakthrough in solar cell technology, developing a microscopic monitoring method to observe the self-repairing mechanisms within high-efficiency silicon cells when exposed to ultraviolet (UV) light and subsequent sunlight. This innovation promises to reshape how solar panels are tested, designed, and certified for long-term performance in real-world conditions.
The research, spearheaded by Scientia Professor Xiaojing Hao and published in Energy & Environmental Science, offers a detailed look at the chemical changes occurring inside solar cells as they degrade and recover. The UNSW team included Dr. Ziheng Liu, Dr. Pengfei Zhang, and Dr.Caixia Li.
“This new method can be used directly on the production line to quickly check how well solar cells resist UV damage,making it useful for future quality control during manufacturing,” explained Prof. Hao. silicon solar cells are known to lose efficiency over time due to exposure to ultraviolet radiation – a phenomenon known as ultraviolet-induced degradation (UVID). Previous studies have indicated performance drops of up to 10% after 2,000 hours of accelerated UV exposure.
while experts have long recognized that solar cells regain some lost performance when exposed to normal light.
At the microscopic level, UV light alters chemical bonds involving hydrogen, silicon, and boron atoms near the cell surface, weakening the material’s quality and reducing performance. The team was able to directly observe these bond changes for the first time. Later, when exposed to visible light, the chemical structure returned to its original state, with hydrogen atoms migrating back to the surface and broken bonds being repaired.
“This confirms that recovery is not just an electrical effect,” Dr. Liu stated. “The material itself is repairing at the atomic level.”
Implications for the Solar Industry
The ability to directly observe these reversible material changes has important implications for the solar industry. Current solar panel certification relies on accelerated aging tests that simulate years of outdoor use through intense UV radiation. However, if degradation is reversible under normal sunlight, these tests may overestimate losses and even induce damage that wouldn’t occur in real-world conditions.
By distinguishing between temporary and lasting changes, the new monitoring method provides a scientific basis for improving these tests. “This approach helps distinguish between true long-term degradation and reversible changes,” Dr. Liu explained. “That distinction is essential for accurate lifetime prediction.”
Beyond its scientific value, the Raman-based method offers practical advantages. Traditional UV degradation tests can take weeks and ofen require destructive analysis, while the new method can detect UV sensitivity in seconds without damaging the cell. This speed and realism make it ideal for manufacturing, enabling rapid feedback and quality control. researchers suggest it could be used to screen new materials, processing conditions, and design changes before full-scale panel production.
Supporting Better Solar Panel Design
The monitoring method also sheds light on why some solar cells degrade more then others. By observing material-level changes, the researchers demonstrated how design choices – such as passivation layer thickness and surface coating properties – influence hydrogen movement during UV exposure and recovery. This knowledge empowers manufacturers to make informed trade-offs between efficiency, durability, and cost.
Notably, the study suggests that a solar cell that temporarily degrades and then recovers may outperform a more expensive, fundamentally UV-resistant design over its lifetime. “This work gives us a clearer picture of how solar cells behave in the real world,” Prof. Hao concluded. “With better monitoring tools, we can design better tests, better panels, and ultimately more reliable solar energy systems.”
More information: Pengfei Zhang et al, A non-destructive UV Raman characterisation platform to enable insight into the mechanism of reversible ultraviolet-induced degradation (UVID) in TOPCon solar cells, Energy & Environmental Science (2026). DOI: 10.1039/d5ee05078b.
Provided by University of New South Wales.
