This study presents the design, installation, and performance evaluation of a 3.5 kVA solar photovoltaic system integrated with a 3kWh (24V) lithium battery at the Directorate of Research and Development, Kaduna Polytechnic. Developed using systematic load assessment and proper component sizing, the system comprises a 2kW PV array, hybrid inverter with MPPT, and battery storage, providing stable voltage output (220–230 V), efficient energy conversion, and reliable backup during grid outages. The lithium battery exhibited high charging efficiency (~90%) and long cycle life (>6000 cycles), ensuring operational sustainability. Implementation significantly reduced reliance on the unstable grid, minimized downtime for critical research equipment, and enabled uninterrupted power supply through effective solar– battery–grid integration. The results demonstrate that medium-scale solar PV systems are technically feasible, reliable, and economically viable for institutional applications, offering a scalable framework for renewable energy deployment in tertiary institutions.