An inadequate understanding of the energy needs of forcibly displaced populations is one of the main obstacles in providing sustainable and reliable energy to refugees and their host communities. Here, we provide a first-order assessment of the main factors determining the decision to deploy fully renewable mini-grids in almost 300 refugee settlements in sub-Saharan Africa. Using an energy assessment survey and publicly available traditional and earth observation data, we estimate a total electricity demand of 154 GWh yr–1. This figure includes lighting, air circulation and phone charging for 1.15 million households and the estimated demand of almost 59,000 microbusinesses and around 7,000 institutional loads. Using a set of techno-economic modelling tools, we thus compute a corresponding upper-bound total up-front cost of providing electricity access of just over US$1 billion. Deploying solar photovoltaic mini-grids instead of diesel implies avoiding greenhouse gas emissions for 2.86 MtCO2e over 20 years.