Reliability Analysis of Residential Photovoltaic Systems Across Five Climatic Zones: Performance, Degradation, and Fault Trends

This study analyses the long-term reliability of 100 residential PV systems monitored for 7–11 years across 33 countries and five climate zones. System performance was evaluated using the temperature-corrected performance ratio (PRTcorr), following IEC 61724-1, while annual degradation rates were calculated using RdTools, which separates long-term trends from interannual variability. Inverter and MPPT reliability were assessed through a defined fault-likelihood metric, representing the percentage of time the measured AC or DC power fell more than 15% below the manufacturer-reported expected power for at least two consecutive intervals. The results show a strong association between climate conditions and system performance. Mediterranean climates record the highest PRTcorr (0.84 ± 0.02), while desert regions show the lowest values (0.73 ± 0.04). Annual degradation rates range from −0.69 ± 0.15%/year in Mediterranean climates to −3.13 ± 0.64%/year in desert climates. Inverter fault likelihood is highest in desert regions (4.05%) and lowest in temperate climates (1.5%), while MPPT fault likelihood ranges from 10.25% in desert zones to 5.4% in Mediterranean zones. By integrating PRTcorr, long-term degradation trends, and inverter/MPPT fault behavior within a cross-climate framework, the study provides an evidence-based understanding of how environmental stressors shape PV system reliability.