UV radiation is a major driver of PV module degradation, but current standards underestimate real-world exposure
Global UV irradiance varies widely, leading to location-dependent degradation behavior
In high-irradiance arid and semi-arid regions, single-axis tracking can result in approximately twice the UV-induced degradation compared to fixed-tilt systems
PV systems are being optimized for higher energy yield. This leads to higher cumulative irradiance over time. While ultraviolet (UV) radiation represents only a small fraction of the solar spectrum, it is a major driver of material degradation. It affects encapsulation, backsheets, and cell interfaces, leading to gradual performance loss.
A paper published in the IEEE Journal of Photovoltaics, titled Closing the UV-Induced Photodegradation Gap Through Global Scale Modeling of Fixed Tilt and Tracking Photovoltaic Systems, examines how well current testing standards reflect real-world exposure. It notes that standards such as IEC 61215 apply a UV dose of 15 kWh/m². In high-UV regions, this level can be reached in less than 50 days.
The study also shows strong geographic variation in UV irradiance. It can range from less than 30 W/m² in high-latitude regions to over 80 W/m² in arid and semi-arid regions. This variation directly influences degradation rates, even for identical module technologies deployed across different climates.
To better represent field conditions, the authors developed a high-precision model to estimate UV exposure on tilted module surfaces. The model shows strong agreement with measured data, with deviations below ±4%. This allows for more accurate evaluation of UV stress under actual installation conditions, including different tilt angles and system configurations.
Single-axis trackers maintain a more optimal angle to the sun and receive higher cumulative irradiance. While this improves energy yield, the study also shows that it increases UV exposure over the module lifetime. The effect becomes more pronounced in high-UV regions. In arid and semi-arid climates, it indicates that modules mounted on tracking systems can experience up to twice the UV-induced degradation (UVID) of fixed-tilt installations. This introduces a trade-off between performance gains and accelerated material aging.
These findings point to the need for climate-specific reliability assessment. A uniform testing approach does not capture the wide variation in UV exposure across deployment regions. Incorporating location-dependent stress factors could support better material selection and improve the accuracy of lifetime predictions.
As tracking systems continue to expand in utility-scale installations, the study highlights an important system-level consideration. Higher irradiance capture improves energy output. At the same time, it increases exposure to degradation drivers that are not yet fully reflected in standard testing.
TaiyangNews’ latest Market Survey on Solar Trackers also looks into tracking configurations and system-level performance, including factors that influence long-term reliability. The survey is available for free download here.
