Some experimental studies mention degradation rates of the order of -0. 3%/year measured as an average on several modules (and measured with very old modules manufactured in the years 80-90, with old technologies). systems reported in published literature from field testing The review consists of three parts: a brief historical outline, an analytical. This paper presents a defect analysis and performance evaluation of photovoltaic (PV) modules using quantitative electroluminescence imaging (EL). The study analyzed three common PV technologies: thin-film, monocrystalline silicon, and polycrystalline silicon. Many Tier 1 modules continue to perform well for 35–40 years, though at reduced efficiency. Performance warranty typically guarantees ≥80% output.