An Evaluation of 27+ Years Old Photovoltaic Modules Operated in a Hot-Desert Climatic Condition

Identification of failure mechanisms from the long-term field deployed modules is of great importance to the photovoltaic industry. This paper investigates the modules removed from a water pumping array operated over 27+ years in a hot-desert climatic condition, Arizona. Thirty-two modules were evaluated in this investigation. Each module is comprised of silicone rubber superstrate/encapsulant, mono-Si cells, fiberglass-like substrate, potted junction box and neoprene cable. Ten of these thirty-two modules were either non-functional or near non-functional with less than 30% of the original power. The other twenty-two functional modules showed an average power degradation of 1.08% per year over 27 years of operation. After the damp-heat (1000 hours of 85degC/85%RH), thermal cycling (two-hundred cycles of 90degC/-40degC) and hot-spot stress tests the modules lost about 11%, 9.8% and 3.5% of power, respectively