Determinants of the long-term degradation rate of photovoltaic modules: A meta-analysis

Abstract

A critical factor in determining the ecological and economic benefits of photovoltaic (PV) investments is the continuous decline in power output, known as degradation rate, and the consequent projected lifespan of the installed modules. To derive the aggregated effect of all degradation rates of outdoor exposed PV modules across the existing literature and explain the large differences among reported rates, we conducted a meta-analysis using various moderator variables, including climatic conditions, cell technology, methodological characteristics, and publication characteristics. The analysis of 80 primary studies, reporting 610 degradation rate observations, revealed a median degradation rate of 0.94 %/year and indicated that cell technology, mounting location, and methodological choices in the study design significantly influence reported degradation rates. We predict an average lifespan of 47 years for well-ventilated crystalline silicon (c-Si) modules in cold climates. These findings provide guidance for the future expansion of the photovoltaic fleet, aiming to enhance long-term performance.