This book contains the study of power quality assessment on grid connected PV system. To accomplish this, 1kWp grid connected solar PV system is modelled and simulated in Matlab/Simulink. The historical environmental data collected over a number of years are used to estimate the profile of the output power of the PV system. The P&O MPPT algorithm is implemented in DC/DC boost converter to enable PV arrays to operate at MPP. Possible operational problems that might arise due to installing PV systems are identified and different strategies that can mitigate these problems are studied in detail. In addition, per year energy generated by the array and energy injected to the grid are evaluated and compared with the array energy at STC. The performance of the system is evaluated with the calculation of performance ratio, grid penetration and power quality under the different climatic condition. Eventually, the source of harmonics and the factors that affect the magnitude of harmonics (THD) in PV grid connected system are identified and analyzed. Different harmonic filtering techniques are tested and the results are compared with the standard values.