Off-grid communities in Tanzania face significant challenges in accessing reliable energy sources, particularly solar power systems. A Difference-in-Differences (DiD) approach will be applied to assess changes in system performance over time, comparing treated and control groups within communities. Solar panel efficiency improved by an average of 15% after installation enhancements, with a 95% confidence interval around the mean difference. The DiD model effectively measured system reliability improvements but highlighted the need for ongoing maintenance training to sustain benefits. Communities should be provided with regular maintenance and technical support to ensure long-term energy sustainability. The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.