Progress Update: Task Group 5
Task Group 5 is focused on the effects of light and how these effects are related to temperature and humidity.
Light (especially UV light) can cause changes in modules including solarization of the glass, light-induced degradation in the cells, discoloration, and decrease in adhesion. Unfortunately, application of light in large areas is expensive, so a strategy has often been to apply the stresses to a smaller version of a module. This scope is closely related to the scope of Task Group 3.
Having surveyed equipment that is being used for UV exposure testing in the industry, a round robin is being conducted to compare the degradation of a set of samples to different light sources. Studies include the development of an acceleration factor for EVA yellowing and adhesion and back-sheet round robin testing with different UV-test sources. A four-cell mini-module test program is also underway in Japan in collaboration with Task Group 3, which is investigating test sequences combining irradiation intensity, temperature, and humidity.