Energy storage devices and renewable energy sources work together to improve the stability of the power grid. This chapter examines the WSCC 9-bus system with a combined Photovoltaic (PV) and Battery Energy Storage System (BESS) to assess transient stability and load variations. MATLAB 2021b is used for research enabling precise power system modelling. To increase the efficiency of data transmission and analysis, the simulation process is mechanized using an Application Programming Interface (API) based approach. Important factors like voltage stability, frequency variations, and power oscillations under various load circumstances are analysed by time-domain simulations. The findings show that by lowering voltage and frequency variations, PV-BESS integration improves transient stability. The API-driven methodology is a useful tool for power system research since it also simplifies the analytical procedure. This study sheds light on the development of smart grids and the function of hybrid renewable energy systems in contemporary power networks.