Analysis and prediction of the performance and reliability of PV modules installed in harsh climates: Case study Iraq

The increasing global demand for renewable energy necessitates a comprehensive understanding of solar photovoltaic (PV) system performance and reliability, particularly in harsh climates such as Iraq. Despite ambitious targets to diversify its energy sector, Iraq faces challenges in the deployment of PV projects due to limited field experience. In this study, we assess the reliability and performance of two different PV systems installed in Basrah and Baghdad, aged 3.5 and 8 years, respectively. Field analysis reveals prevalent issues including glass and cell breakage, delamination, solder bond fatigue, and encapsulant discoloration, contributing to medium degradation rates of 0.91%/year and 2.6%/year in Basrah and Baghdad, respectively. Our investigation attributes higher degradation rates not only to ageing but also to suboptimal operation and maintenance (O&M) practices. Additionally, since the two systems are from different manufacturers, we verify that the measured higher degradation rates are mainly attributed to harsh operating conditions rather than differences in manufacturing processes. To extrapolate our findings countrywide, we employ a physics-based model to simulate the degradation rates. Based on the simulated degradation, we proposed four degradation rate zones across the country with degradation rates ranging from 0.62 %/year to 0.96 %/year. By applying these rates to estimate lifetime energy yield across different zones, we demonstrate the trade-offs between higher irradiance zones with reduced PV lifetime and low irradiance zones with longer PV lifetimes. In the study, we compared energy yield simulations using fixed degradation rates with those employing climate-dependent degradation rates. Our analysis revealed that in certain locations in Iraq, employing a fixed degradation rate underestimates the yield by approximately 9.7%. Conversely, in other locations, it results in overestimations ranging from approximately 10.5% to 31.1%, highlighting the importance of accurate degradation rate modelling for PV system assessment. Furthermore, we simulate the impact of soiling losses on energy yield, revealing potential losses of up to 70% depending on location and cleaning schedules. Our findings contribute valuable insights into PV system degradation across harsh climates, addressing critical gaps in global degradation rate data and facilitating more accurate climate-dependent assessments of PV performance and reliability.