A multi-criteria, long-term energy planning optimisation model with integrated on-grid and off-grid electrification – The case of Uganda

•Most sub-Saharan African countries have low and unequal access to electricity.•Multi-objective optimisation model integrates grid and off-grid electrification.•Solar energy is the cost-minimal strategy to minimise electrification inequality.•Off-grid electrification is a crucial component of all optimal solutions in Uganda.•Uganda’s current official expansion plan is infeasible and would be sub-optimal.