Off-grid communities in Tanzania are increasingly relying on solar-powered water pumping systems for domestic and agricultural use. The study employed a mixed-method approach, combining quantitative analysis with qualitative insights to assess system reliability over time. Panel data analysis revealed that solar efficiency varied by up to 15% across different seasons, with higher variance in the dry season compared to the wet season. The findings suggest a need for seasonal adjustments and improved system maintenance strategies to enhance overall reliability. Communities should be encouraged to adopt adaptive management practices based on local climate conditions. Off-grid systems, solar-powered water pumping, panel data analysis, reliability, Tanzania The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.