Operational and economic impacts of extreme weather on PV power plants

In an anthropocentric world increasingly defined by changes in atmospheric chemistry, two clear trends have emerged. One is the increase in the frequency and severity of extreme and anomalous weather events, the latter driven by rising temperatures and changing patterns of humidity and precipitation; the other is the rapid acceleration of photovoltaic (PV) capacity worldwide, reaching 2 TW in 2024 on course for the expected 8 TW by 2030. To ensure the further growth and development of PV systems worldwide, however, requires attention to both trends and especially to opportunities for designing PV systems to withstand specific storm threats. Although there are many examples of solar technologies being deployed without consideration for their storm resilience per se, design optimization is gaining attention as solar energy continues to proliferate across almost all climate zones. This report provides a comprehensive look at changing weather patterns and their anticipated impact on the reliability and performance of PV systems worldwide. Broken down by storm category, the report covers extreme weather events of greatest significance to PV power plants: tropical cyclones, convective storms, snowstorms, dust storms, heat waves, floods and wildfires. For each category, an overview of the threat landscape is provided, along with best practices for design and procurement, mitigation strategies, post-storm assessment and follow-on O&M. The report also considers damages to PV systems that can be 1) catastrophic, as in, the total destruction of modules, strings or entire systems: modules unravel from their mounts, racks collapse, and glass shatters; e.g., tropical cyclones, convective storms (including hail), and flooding (see Table 1 below); and/or 2) sub-catastrophic, as in, visual inspection results in no detectable damage, even though internal damage may have occurred to the solar cells or other module components; e.g., snow, dust storms, heatwaves, and wildfires (see Table 1 below). Detectable only with costly imaging techniques, such as infrared or electroluminescent imaging, undiagnosed damage may deteriorate over time, resulting in accelerated performance degradation or the accelerated senescence of module components, such as backsheets and encapsulants. In addition, the report acknowledges the rapid pace of technological innovation in the solar industry, including the proliferation of new materials and components, the long-term reliability of which is largely unknown, especially under extreme-weather conditions where modules and other components are subjected to combined and cyclic forces not captured by accelerated testing. The resilience of a PV system during extreme weather depends heavily on the unique characteristics of each storm — including the number and types of stressors, how these stressors interact in unpredictable ways, and how such interactions affect the system’s components. Even so, certain generalizations around best practices can be made: 1) site planning should always include a review of weather threats at that particular site; and 2) design and procurement decisions should be based on the threat landscape. In hail-prone regions, for example, modules with thicker front glass are preferred; in snowy regions, frameless outperform framed modules; in regions where tropical cyclones are the primary risk, consideration must be paid not only to the module architecture but even more to the fasteners and other hardware that hold the system together. Stow algorithms for single-axis trackers should also be validated via track records of damage prevention. In addition, each site must have a set of protocols and response strategies specific to the weather threat and be prepared to follow them on short notice. And last, but not least, the operational status of a plant must be considered. Sites under construction are more prone to erosion because ground cover is lacking, to wind damages because modules may not be properly fastened and are susceptible to flying debris, and to electrical damages, if cable and connectors are exposed to moisture.