Optimal sizing of a mini-grid in developing countries, taking into account the operation of an electrochemical storage and a fuel tank

Nowadays, mini-grids can provide reliable and cheap electricity also to far communities of developing countries. Diesel generators can ensure backup power, in addition to renewable sources and energy storage devices. However, poor infrastructures, severe weather conditions and a difficult procurement chain can strongly influence the fuel delivery, thus reducing the continuity of supply. The present paper proposes a stochastic method to optimize the design of a rural mini-grid composed by a photovoltaic plant, a lithium battery, a diesel generator and a fuel tank. The fuel procurement strategy and its mathematical model are also discussed and simulated. A Particle Swarm Optimization (PSO) procedure is applied to the optimal sizing of components, in combination with a Monte Carlo technique aimed to handle the uncertainties of fuel delivery, irradiance and load. A case study for a possible mini-grid in Uganda is discussed, also performing a sensitivity analysis of the results with respect to the fuel delivery time, the fuel price and the cost of load curtailment.