Techno-Economic Optimization of a Grid-Tied PV/Battery System in Johannesburg’s Subtropical Highland Climate

Webster J. Makhubele, Bonginkosi A. Thango () and Kingsley A. Ogudo
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Webster J. Makhubele: Department of Electrical Engineering Technology, University of Johannesburg, Johannesburg 2092, South Africa
Bonginkosi A. Thango: Department of Electrical Engineering Technology, University of Johannesburg, Johannesburg 2092, South Africa
Kingsley A. Ogudo: Department of Electrical Engineering Technology, University of Johannesburg, Johannesburg 2092, South Africa

Sustainability, 2025, vol. 17, issue 14, 1-21

Abstract: With rising energy costs and the need for sustainable power solutions in urban South African settings, grid-tied renewable energy systems have become viable alternatives for reducing dependence on traditional grid supply. This study investigates the techno-economic feasibility of a grid-connected hybrid photovoltaic (PV) and battery storage system designed for a commercial facility located in Johannesburg, South Africa—an area characterized by a subtropical highland climate. We conducted the analysis using the HOMER Grid software and evaluated the performance of the proposed PV/battery system against the baseline grid-only configuration. Simulation results indicate that the optimal systems, comprising 337 kW of flat-plate PV and 901 kWh of lithium-ion battery storage, offers a significant reduction in electricity expenditure, lowering the annual utility cost from $39,229 to $897. The system demonstrates a simple payback period of less than two years and achieves a net present value (NPV) of approximately $449,491 over a 25-year project lifespan. In addition to delivering substantial cost savings, the proposed configuration also enhances energy resilience. Sensitivity analyses were conducted to assess the impact of variables such as inflation rate, discount rate, and load profile fluctuations on system performance and economic returns. The results affirm the suitability of hybrid grid-tied PV/battery systems for cost-effective, sustainable urban energy solutions in climates with high solar potential.

Keywords: grid-tied PV system; battery energy storage; techno-economic analysis; HOMER Grid; subtropical highland climate (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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