Abstract— This study aims to investigate the effectiveness of Unified Power Quality Conditioners (UPQC) in reducing the power quality issues and harmonics caused by non-linear loads in the power grid. Here the Photovoltaic (PV) is integrated with Battery Energy Storage System (BESS) to enhance the power quality. During emergencies, the BESS supplies backup power over prolonged voltage interruptions or when the PV system is unable to meet the required power demand. A hybrid PV-BESS system is found to be more reliable than a standalone PV-UPQC system due to its ability to produce continuous clean energy and increase voltage support capacity. The UPQC controller is synchronized using the unit vector generator (UVG) approach in conjunction with the self-tuning filter (STF). The STF-UVG approach ensures normal UPQC operation even in the presence of distorted and imbalanced grid voltage. The proposed methodology is verified through MATLAB-Simulink simulations and various case studies.