Off-grid community energy systems are increasingly adopted in rural Tanzania to address electricity access challenges. A quasi-experimental design was employed to compare pre- and post-intervention costs and benefits among participating communities. The analysis revealed significant reductions in average energy costs by $15 per household month (p < 0.05), with notable improvements in access reliability. The quasi-experimental design provided robust evidence of cost-effectiveness for off-grid community energy systems, offering a viable solution to rural electrification challenges. Further studies should focus on scaling up and replicating these findings across Tanzania’s diverse regions. Off-grid communities, Energy access, Cost-effectiveness, Quasi-experimental design, Rural electrification Model estimation used $\hat{\theta}=argmin_{\theta}\sum_i\ell(y_i,f_\theta(x_i))+\lambda\lVert\theta\rVert_2^2$, with performance evaluated using out-of-sample error.