Cost-efficient energy supply through PV off-grid systems: An approach to electrifying rural areas in Africa

Abstract:
Electrifying rural areas in Africa is one of the central challenges to sustainably improving the quality of life for the population [1]. The lack of energy infrastructure, high production costs, and the instability of energy supply make access to electricity particularly challenging [2]. Containerized solar systems offer a modular and rapid solution to supply energy to remote communities [3]. However, the cost per kilowatt-hour remains disproportionately high due to reliance on im-ported components, outdated battery storage, inefficient operational models, and the incorrect sizing of system compo-nents [4]. These incorrect dimensionings often result from incomplete data, both in terms of actual energy demand and production. This study presents an approach to creating a data foundation that enables the simulation and optimization of energy systems. Dioumatene, a typical rural village in Mali, was selected for this study because approximately 80 % of Mali's population lives in rural areas where access to electricity is extremely difficult. Additionally, the village already has an energy system that provides a relatively reliable electricity supply compared to other villages in the region, allowing consumption data to be collected with only minor gaps. The energy system in Dioumatene includes a 40 kWp photovoltaic system (PV) and a 63 kWh battery storage system, with a usable capacity of approximately 50 kWh. It supplies electricity to 300 house-holds with an annual energy consumption of 18 MWh, equivalent to the annual energy needs of about six households in Germany. The load cycles – characterized by increased energy demand during nighttime – reflect typical consumption patterns in rural communities, where electricity is primarily used for lighting, refrigeration, air condition and mobile devices [6]. This study aims to identify improved energy systems for Dioumatene that can provide a more stable electricity supply while minimizing energy costs. The identified solutions are intended to serve as examples for similar systems in rural Mali, as their component sizes can be scaled according to the population size. The primary energy source for such a system should be a PV system, as each installed kWp in Mali can generate 2.000 kWh of electricity annually. Aside from minor fluctuations during the rainy season, PV systems offer a highly reliable energy source [5]. To meet the increased nighttime demand, batteries are an essential component of the energy system. The study identified two energy systems that are particularly well-suited to meet the needs of the village. The first is a fully self-sufficient energy system comprising a 16 kWp PV system and a battery storage system with a capacity of 68 kWh. This system provides stable energy supply without dependence on energy imports but comes at a higher cost of 70.400 € over ten years. The majority of these high costs are driven by the battery storage, whose full capacity is rarely utilized. Therefore, the second system is a hybrid energy system that includes an 11,5 kWp PV system, a significantly smaller 38 kWh battery storage, and a 3-kW-generator. This system requires 209 liters of petrol annually to operate the generator and costs 46.535 € over the same period, including generator and fuel costs. While it offers greater flexibility at lower costs, it depends on petrol imports. The findings demonstrate that significant advantages can be achieved through the use of modern technologies such as lithium-ion batteries and monocrystalline PV modules [7]. However, fully meeting energy needs solely with these com-ponents is not necessarily the most economical solution. The results from [8] show that targeted adaptation to cultural and climatic conditions can significantly enhance efficiency and reduce costs.