UNSW researchers have devised a process that identifies exactly how solar cells are damaged by ultraviolet radiation - and what happens when they naturally recover thanks to the sun.
Engineers at UNSW Sydney have developed a way to monitor solar cells at a microscopic level while they are operating - to discover exactly how damage caused by ultraviolet light can be naturally repaired.
The new monitoring method allows experts to directly observe chemical changes inside high-efficiency silicon solar cells as they degrade under UV exposure, which in turn is expected to help develop processes that can help the cells recover using normal sunlight.
The research, led by Scientia Professor Xiaojing Hao and published in Energy & Environmental Science , could significantly transform how solar panels are tested, designed, and certified for long-term outdoor use.
"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," says Prof. Hao.
Silicon solar cells suffer a reduction in their efficiency and performance over time due to exposure to ultraviolet radiation - known as ultraviolet-induced degradation (UVID).
Some previous studies have shown the drop in performance can be as high as 10% after the equivalent of 2000 hours exposure to UV radiation during accelerated testing.
Photovoltaic experts have long known that solar cells can recover some of this lost performance when exposed to sunlight during normal operation - but this recovery had only been observed in terms of electrical output and it remained a mystery what was actually happening inside the material.
Without that understanding, it has been difficult to determine whether UV-related performance losses are permanent, how serious they are, and how well current testing standards reflect real-world conditions.
The UNSW-led team, including Dr Ziheng Liu , Dr Pengfei Zhang and Dr Caixia Li, addressed this challenge by developing a new, non-destructive monitoring technique that can track material-level changes inside a working solar cell.
They used a technique called ultraviolet Raman spectroscopy that identifies a material by shining a laser on it and analysing how the light scatters to reveal the material's molecular vibrations.
This method allowed the researchers to observe chemical bonding near the surface of the solar cell while it was being exposed to UV light and during recovery under visible light. At all times the cell remained intact. And it can be used for cells operating under realistic conditions.
