Accelerated Test For Light-Weight Photovoltaic Module Encapsulants

Light-weight photovoltaic (PV) modules can be easily integrated into buildings, vehicles, portable electronics, and many other special applications, thus leading to many potential markets for photovoltaics. In this work, we investigate the performance of several conventional and new module materials under damp-heat and pressure cooker tests with 105 degrees C 85% relative humidity (RH) for the development of reliable light-weight PV. The top layer includes the conventional polyethylene terephthalate (PET), ethylene /tetrafluoroethylene (ETFE) sheets and also a biocompatible, weather durable silicone/polyurethane (PU) composite material, named as Compo-SiL (R), while the bottom layer is the conventional Tedlar/PET/Tedlar (TPT) back sheet. We also compare the performance of a thermal polyurethane (TPU) with the conventional ethylene vinyl acetate (EVA) as the encapsulant. A single 6-inch polycrystalline solar cell is laminated with a combination of the materials above and then undergone the accelerated tests and periodical analyses of electrical performance, change of appearance, electroluminescence imaging. We have found that TPU as an encapsulant performs better than EVA under damp-heat test for 1000 hours, where the power conversion efficiency was not affected at all. However, TPU fails at the pressure cooker test with 105 degrees C and 85% RH. On the other hand, the Compo-SiL (R), a silicone/polyurethane (PU) composite material as the top layer performs better than the PET and ETFE under the pressure cooker test. The efficiency degradation is less than 10% after 1000 hours. These preliminary results may stimulate further research effort in the development of light-weight PV encapsulation.