Performance Evaluation of Energy Storage Systems in Off-Grid Renewable Energy Installations in Taraba State

Background: Energy storage is the most critical and expensive component of off-grid renewable energy systems serving communities without grid access in Taraba State, North East Nigeria. Performance degradation and premature failure of storage systems are common challenges. Aim: This study evaluated the performance of battery energy storage systems in off-grid solar installations across seven communities in Taraba State. Methods: State of health, capacity fade, and charge-discharge efficiency were evaluated for lead-acid, lithium iron phosphate, and gel battery systems at 21 installations using a battery analyser and datalogger. System operating histories spanning 2 to 5 years were obtained. Results: Lead-acid batteries exhibited mean capacity fade of 38% after 3 years, significantly exceeding manufacturer specifications. Lithium iron phosphate systems retained 91% capacity after equivalent service. Charge controller mismatches and overcharging were identified as primary degradation causes in lead-acid systems. Life cycle cost analysis favoured lithium iron phosphate despite higher upfront cost. Conclusion: Lithium iron phosphate storage is more economical and reliable for off-grid systems in Taraba State. Proper charge controller sizing and user training on battery maintenance are critical to extending storage system life. Keywords: battery storage, off-grid solar, energy storage, Taraba State, lithium iron phosphate.