The Maximum Power Point Tracking (MPPT) by Fixed Voltage Method in a Solar Photovoltaic (PV) System implemented in MATLAB involves controlling the voltage to achieve maximum power output from the solar panels. This method adjusts the operating voltage of the PV system to track the point where maximum power is generated, despite variations in solar irradiance and temperature. By simulating the system in MATLAB, engineers can analyze and optimize the MPPT algorithm's performance, ensuring efficient energy conversion and maximizing the solar PV system's overall output.