Off-grid PV systems for rural electrification

Abstract

To this day, 16% of the world’s population still has little or no access to electricity. The majority of which is located in rural regions of developing countries, such as India and most countries in sub-Saharan Africa. As a part of the Sustainable Energy for All (SE4All) initiative, a multi-tier framework that aims to categorize and quantify the electricity access of households and rural regions to reach the sustainable development goals by 2030. Solar Home Systems (SHS) is a potential solution that has emerged to cater for the lighting and power needs of these remote households. SHSs consist of a small stand-alone DC system which are composed of a PV array, battery, and power electronics that are designed to meet the load of a single household. The aim of this study is to propose a universal, optimal sizing methodology for the SHS with respect to cost, reliability (LLP) and battery lifetime for any household in the mutli-tier energy ladder. Moreover, the study aims to anticipate to which extend a stand-alone architecture remains a feasible solution. In this thesis, a practical model for each of the Solar Home System components was built using MATLAB, then two optimization methods: a classical iterative method, and the Genetic Algorithm, an evolutionary method were used to perform a multi-objective optimization on three case studies in different locations. The results obtained showed that for the lower energy tiers, with a load profile up to a peak load of 155W, the standalone approach is optimal. With an LLP·2%, an average total upfront cost of 1600$, and a lead-acid battery lifetime of 6.5 years. The results from the higher tiers however show proved that as the household moves up the energy ladder, the stand-alone approach becomes unaffordable and less reliable. An alternate approach to solve this issue was examined, where several households are interconnected forming a minigrid to share their energy generation and load. The outcome of this study showed that households with sub-optimal sized Solar Home Systems were able to greatly increase their system reliability, the LLP was recorded to drop by up to 50% in some scenarios with an increasing number of interconnected households. The LLP drop however reached a saturation point beyond 25 households. On this basis, it is recommended that further work should be done to increase the complexity of the component models, notable the battery. Moreover, a more extensive study should be conducted on the interconnected approach, with a multitude of scenarios to optimize the system size in a mini-grid architecture.