Analytical model for optimal energy storage sizing in low voltage networks in South Africa

Energy storage plays a pivotal role in integrating renewable energy sources into low-voltage (LV) networks, especially in South Africa, where electricity grids are plagued by challenges such as reliability issues, frequent load-shedding, voltage instability, and aging infrastructure. This paper presents a comprehensive mathematical framework for optimizing the sizing of battery energy storage systems (BESS) in South African LV networks. The model focuses on minimizing the total cost of ownership (TCO) by balancing the trade-offs between capital investments, operational expenses, and lifecycle costs of energy storage systems. Additionally, the study aims to enhance grid stability by mitigating voltage fluctuations, reducing peak loads, and improving frequency regulation, all of which are critical for ensuring the resilience of the power network. By enabling smoother integration of intermittent renewable energy sources, particularly solar photovoltaic (PV), the model also seeks to maximize renewable energy utilization by minimizing energy curtailment and storing surplus energy for later use. Furthermore, the optimized BESS configuration helps reduce peak grid imports by discharging stored energy during periods of high demand, thus decreasing reliance on centralized generation and alleviating the impacts of load-shedding. Using mixed-integer linear programming (MILP) and real-world data on energy demand and renewable generation profiles, the study reveals that optimal BESS sizing can reduce the total cost of ownership by up to 25%, curtail renewable energy wastage by 15%, and lower peak grid imports by 30% These findings provide actionable insights for policymakers, energy planners, and stakeholders, emphasizing the critical role of BESS in transforming South Africa's LV networks into more resilient, sustainable, and economically efficient systems while addressing growing energy demands and renewable integration challenges.