Reliability analysis and maintenance scheduling of solar photovoltaic systems using FMEA: A case study of Lango, Uganda

This study examines the reliability and maintenance of solar photovoltaic (PV) systems in Lango, Uganda, using a descriptive survey of 280 respondents, site observations, Failure Modes and Effects Analysis (FMEA), and exponential reliability modelling. Aggregate reported-event counts were 460 for solar panels, 965 for batteries, 690 for inverters, and 310 for charge controllers. Using a nominal exposure of 102,200 component-days per class, estimated event rates were 0.004501, 0.009442, 0.006751 and 0.003033 day⁻¹, respectively, with corresponding 95% Poisson/chi-square confidence intervals of 0.004099–0.004932, 0.008856–0.010057, 0.006257–0.007275 and 0.002705–0.003390 day⁻¹. Under an independent exponential series model, calculated system reliability was 1.40% at 180 days and 0.01733% at 365 days. These estimates are conditional on nominal exposure and unverified classification of reported events as functional failures. An analytical cost and availability model compares corrective, age-based, and grouped maintenance policies. The constant-hazard model predicts no preventive-maintenance reliability gain; an optimal interval requires intervention costs, outage durations, and measured maintenance effects. The findings identify priorities for validating operational records and developing component-specific maintenance policies.