Field Assessment of a Rooftop Solar Photovoltaic–battery Hybrid System for Carbon-emission Mitigation at a Remote Site in Ngorongoro, Tanzania
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Abstract
Sub-Saharan Africa must extend electricity access while restraining the growth of energy-sector carbon emissions. Distributed solar photovoltaic (PV) generation with battery storage is widely proposed to reconcile these aims, yet measured field evidence quantifying the achieved mitigation for small installations in remote East-African settings is scarce. This paper reports a measurement-based assessment of a rooftop PV–battery hybrid system monitored at Wasso, Ngorongoro District, Tanzania, over 165 recorded days of operation (20 January to 14 July 2026). Daily telemetry of production, consumption, grid exchange and battery activity was analysed to establish the energy balance, self-sufficiency, inferred system rating and avoided carbon emissions. The system, whose array is inferred at approximately 20 kWp, generated 8 797 kWh at a specific yield of the order of 970 kWh/kWp/yr; effectively all output was consumed on-site, meeting 51.7% of the 14 739 kWh site demand at an inferred storage round-trip efficiency of 79.3%. Applying displacement factors of 0.53 kgCO2/kWh (grid) and 0.80 kgCO2/kWh (diesel), and deducting embodied life-cycle emissions, the installation avoided 4.24–6.62 t of CO2 over the window, equivalent to 9.4–14.6 tCO2/yr and to roughly 220–344 t across a 25-year service life. The solar resource is characterised from validated satellite databases, metering accuracy is stated by reference to recognised standards, and the reported avoided-emission figures carry a propagated measurement uncertainty. The near-zero export confirms that correct storage sizing is central to maximising on-site displacement. A multi-parameter sensitivity analysis confirms the displacement emission factor as the dominant assumption, and the measured performance metrics are benchmarked against published reviews and against recent African field studies, which independently identify curtailment as a principal loss channel in operating mini-grids. The results provide an empirical reference for renewable-energy engineering practice and competency-based teaching.
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