This study investigates the technical and economic impacts of integrating energy storage systems (ESS) into grid-connected photovoltaic (PV) systems using the electrical network of a Palestinian village as a case study. Four different configurations of PV and sizes of ESSs are compared to assessing their impact on the most critical grid performance parameters, including voltage regulation, energy loss reduction, and dynamic load control. Utilizing ETAP for simulation, the study also analyzes actual grid behavior under real conditions, total harmonic distortion due to the PV inverter, and reverse power flow when there is high PV penetration. Harmonic distortion was found to be moderate in Case 0 and to increase in Cases 1 and 3, with Case 3 showing the highest distortion at low-voltage buses. Case 3 showed reverse power flow with very little export to the upstream grid, underscoring the significance of control mechanisms at high penetration levels. Economic efficiency is assessed considering the System Advisor Model (SAM) with high focus on main indicators like payback period, net present value, and levelized cost of energy. In all cases, Case 1 is the most efficient and feasible with the smallest levelized cost of energy of 17.4 cents/kWh and a payback period of 8.2 years. Case 2 and Case 3 indicate the best performance; the increased investment cost reduces their economic efficiency. The conclusion is that Case 1 has the optimal trade-off between technical effectiveness and economic viability, and it is an acceptable solution for grid stability, power quality management, and peak-shaving in small- to medium-size applications. The report wraps up by recommending longer-term investigation of hybrid energy storage technology, predictive algorithms, and long-term service reliability of energy storage under the conditions of diverse grids
