The paper here presents the modelling of grid-connected solar photovoltaic system with LCL filter design with Voltage Source Converter control. The system model comprise of PV Array, Boost Converter, Voltage Source Inverter, LCL Filter, Utility Grid and Loads. The Boost converter makes fluctuating input DC to constant output DC .Voltage Source Inverter converters DC boost voltage to three phase AC voltage. The VSC has been controlled through a control unit comprising of the outer and inner control loops. The harmonics in the system has been caused by the power electronics devices and non-linear loads connected in the system and the presence of these harmonics in the system has reduced the power quality and operation of the system. In order to mitigate the harmonics and improve the power quality of the system a LCL filter has been used and its value has been calculated to reduce voltage and current harmonics below IEEE standards. The synchronization of the three phase output of the inverter to grid has been done through PLL. The modelling of the system has been done in MATLAB and an analysis of the system will be done on steady state of the grid voltage and current THD and inverter current THD. The THD of the grid currents has also been compared at two different values of solar irradiance.