Ultraviolet (UV) radiation accelerates the degradation of photovoltaic (PV) modules, both at the cell and module levels, leading to reduced efficiency and a shorter lifespan. While reliability testing has advanced, current standards often fail to reflect real-world UV exposure, especially across diverse climates. Global UV irradiance varies widely, from <30 W/m(2) in high-latitude regions to >80 W/m(2) in arid zones, while standard tests such as IEC-61215 only test up to a dose of 15 kWh /m(2) that can be reached in less than 50 days in some locations. This study develops a high-precision model to estimate UV radiation on tilted surfaces and assesses the influence on UV photodegradation. The model shows minimum bias (<+/- 3.87 W/m(2), i.e., <+/- 4.28%) when compared with observations. Results show notable global variation in UV irradiance on tilted surfaces between single-axis tracking (SAT) and fixed-tilt systems, hence affecting degradation rates. SAT systems experience approximately twice the degradation in arid and semi-arid climates compared to fixed-tilt systems, where UV exposure is most intense. These findings highlight the critical need for climate-specific degradation assessments even for identical module technologies. To ensure outdoor durability and long-term performance, advanced regionally adaptive reliability testing thresholds should be adapted for better-informed material selection and manufacturing.