UV Exposure and Durability of Emerging Photovoltaics: Quantifying and Reporting Outdoor UV Doses

Ultraviolet (UV) radiation in sunlight is well known to harm components of solar modules, especially those of emerging photovoltaic technologies. Current accelerated UV tests, however, differ in spectral range and by orders of magnitude in intensity and dose. Their usual anchors, IEC 61215-2 preconditioning at 15 kW h m–2 and a fixed UV fraction of AM1.5G, do not represent long-term outdoor exposure. Here, we quantify annual outdoor UV doses (280–400 nm) across the contiguous United States from the National Solar Radiation Database for horizontal, fixed-tilt, and tracked mounting. Spectroradiometer measurements at two sites validate the model. Annual horizontal-plane doses span 72–133 kW h m–2, with a median of nearly 100 kW h m–2, so IEC 61215-2 preconditioning simulates only 1.4–2.5 months of outdoor exposure. Single-axis and dual-axis tracking typically add 10 and 18 kW h m–2, respectively. Finally, we propose reporting the source spectrum and expressing the test dose as a multiple of the annual outdoor dose for a stated location and mounting.