Africa contains a significant portion of the world’s population who are in energy poverty. The Sub-Saharan region, in particular, is laden with low electrification rates and high energy prices. This restricts affordable and reliable energy access, specifically in urban slums and rural communities. Decreasing component costs, such as photovoltaic (PV) modules have allowed for renewable energy systems to compete with fossil fuels and in some cases, can also gain an economic as well as environmental advantage. This study looks at the feasibility of incorporating PV into the many existing diesel-fueled mini-grids in Tanzania, offering a hybrid renewables-based system using HOMER software. Using the net present cost (NPC) and levelised cost of electricity (COE) designs were optimised to provide cleaner and cheaper electricity, when compared to the existing diesel counterparts. A hybrid PV-diesel system with battery storage proved the most economical with a COE of $0.29/kWh compared to the diesel-fueled COE of $0.35, a 16% decrease. The NPC for the hybrid model was $1,726,922 compared to $2,056,400 for the diesel model, proving the potential financial benefits of converting mini-grids across Tanzania to renewable energy.