Renewable energy based mini-grids offer a critical solution for universal access to energy in sub-Saharan Africa. We conduct a survey in rural Sierra Leone to measure the perception of local beneficiaries of two solar mini-grid projects vis-à-vis renewable energy potential, community engagement and poverty alleviation. By applying a simple mediation model, we find that the community engagement plays a significant role of chain of influence between renewable energy and poverty reduction - each 1% increase in the perceived renewable energy potential can lead to a 0.195% increase in the perceived poverty reduction, resulting from the community engagement. This mediating effect of the community engagement accounts for around 60% of the total effects of renewable energy on poverty reduction. These findings suggest that empowering the community is essential to creating electricity demand and delivering development impact of renewable energy based mini-grids in the deep poverty context.