Investigation into the impacts of design, installation, operation and maintenance issues on performance and degradation of installed solar photovoltaic (PV) systems

Poor performance and high degradation of photovoltaic (PV) systems reduce the expected power generation and shorten the lifetime of the systems. This study highlighted the design, installation, operation and maintenance issues, and their impacts on the performance and degradation of installed PV systems. The study covered 16 installed PV systems in different climatic zones in Ghana, comprising 104 PV modules of different technologies and ages. Interviews, observation and current-voltage (I-V) curve tracing were used. The results of the study revealed that the installers disregarded the PV system design procedures, leading to undersized systems against the desire demand discussed and agreed on between the owners and installers, and systems whose PV panel capacities exceeded that of the batteries. Consequently, 69% of the systems were improperly sized, resulting in lower power output than expected and failure of some systems. The median power degradation rates were 1.94%/year and 1.34%/year for the shaded and unshaded modules respectively. Four systems had been abandoned while two were partially functioning due to malfunctioning of batteries, inverters and charge controllers, resulting from the use of low-quality components and over-discharged of the batteries due to persistent use of these systems with faulty charge controllers. More than 70% of the systems were installed without easy access to the panels for inspection and cleaning. Consequently, these modules degraded faster than the frequently cleaned modules. The 37.5% of the systems subjected to preventive maintenance degraded at 1.38%/year while the remaining 62.5% subjected to responsive maintenance (maintained only when problems occurred) degraded at 1.61%/year. The disregard of proper procedures by the installers led to undersized systems, panel-battery mismatch and improper installation which resulted in low power output than promised by the installers. The improper operation and maintenance practices such as overloading of systems with inappropriate appliances, over-discharging of batteries, panel shading and lack of regular cleaning resulted in low power output, high degradation rates and components breakdown. The dissatisfaction with the systems performance discouraged the system owners from replacing defective components, leading to abandonment of some of the systems.