Least-cost sizing of PV-battery systems and resilience assessment of PV-wind-battery alternatives for rural healthcare under demand-growth scenarios in Limpopo South Africa

A reliable power supply is important for vaccine cooling, lighting, diagnosis, water pumping, communications, and emergency services at rural healthcare centers. This paper analyzes transparently the comparative pre-feasibility assessment of off-grid PV-battery and PV-wind-battery system configurations for a rural clinic near Polokwane, Limpopo (−23.9045°, 29.4689°), based on specific renewable resource availability data per month, detailed life-cycle replacement schedules, healthcare reliability requirement, and growth-demand profiles. HOMER Pro was applied for hourly analysis and cost ranking, whereas independent energy balances were conducted to cross-check the reported annual figures. At base-case load of 85 kWh/day and 13.8 kW, the optimal design is 70 kW PV, 200 kWh Li-ion batteries, 35 kW bidirectional converter, with no wind turbines, net present cost of $210,075, LCOE of $0.519/kWh, and 0.1% unmet load. An alternative system configuration with diverse sources (55 kW PV, 20 kW wind, 240 kWh battery, 35 kW converter) is kept as an illustration of stress test case and is not economically optimal under the base-case load conditions ($287,546, $0.711/kWh). Demand growth scenarios are analyzed via deterministic scenario and sensitivity analyses. This comparison reveals that high solar exposure favors the PV-battery base case design, while wind power should only be incorporated after measuring the hub height at the site level and determining the additional benefit to reliability. Such a comparison provides a framework for differentiating between least cost design and resilient design alternatives. The ageing of the battery was modelled using a transparent semi-empirical correction for degradation, which related useful capacity and time for replacement to discharge depth, cycles, and temperature.