A grid-connected power system's performance depends on the produced energy's power quality and power coefficient. The higher the power quality of the energy transferred to the grid, the more critical it is for power plants, energy distribution systems and end-users. This study investigated the optimisation possibilities obtained by applying STATCOM (Static VAR Compensation) for a 1 MW PV-based Solar Power Plant (PV-SPP) in the Muğla-Türkiye province. First, the data of components such as the inverter and PV panel that make up the plant were obtained, and the raw MATLAB-Simulink modelling of the plant was carried out. System performance outputs were obtained by adding STATCOM modelling to the obtained modelling. The scientific results of the optimisation would be obtained if this technique was applied to the existing power plant. Since STATCOM also performs the RPC (Reactive Power Compensation) process, it is an up-to-date and effective technique that improves system energy power quality. According to the simulation results, this system with STATCOM draws 24,043% and 11,671% less reactive power and current than the non-STATCOM system.