Comparative study of the performance of field-aged photovoltaic modules located in a hot and humid environment

Long-term monitoring of systems installed in the field is the ultimate standard for evaluating photovoltaic components and systems. This study, which involves the long-term outdoor exposure in a hot and humid climate, intends to address the performance degradation and failure mechanisms which are difficult or impossible to simulate in the lab during time constrained accelerated tests. Experimental data including irradiance, temperature, DC/AC current and voltage has been collected on diverse generations of photovoltaic modules installed throughout the state of Florida. Long term module reliability and lifetime are evaluated using a two pronged approach. 1) Modules have been deployed outdoors for long time periods with systematic - 15 minutes interval- climatic and performance measurements 2) Real-time climatic and performance measurements of modules following long-term outdoor exposed. Visual, IR and electrical insulation inspections were performed are also presented in this paper. Multiple analytical methods are used to quantify energy production and power degradation over time, including Performance Ratio analysis, and PVUSA regression analysis. Real-time field measurements were reviewed for both overall return rates and compare them with the nameplate performance values and to identify the failure mechanism that caused the return.