In MATLAB, implementing harmonic reduction in a grid-connected PV system using a double-tuned filter involves creating a simulation environment that integrates the PV system, grid connections, and the double-tuned filter. The double-tuned filter is designed to mitigate harmonic distortions caused by the PV system's nonlinear loads and switching devices. MATLAB provides tools for designing the filter, simulating its behavior, and analyzing its effectiveness in reducing harmonics. Engineers can optimize the parameters of the double-tuned filter, such as inductance and capacitance values, and evaluate its performance under different grid conditions and load scenarios. Through MATLAB simulations, researchers can assess the impact of the double-tuned filter on grid stability, power quality, and compliance with harmonic distortion standards, ultimately contributing to the improvement of grid-connected PV system performance.