Abstract: With an increasing number of distributed photovoltaic(PV) power stations connecting to the distribution network, the harmonic distortion in the distribution network has risen due to the random fluctuations of PV output and the nonlinear characteristics of the devices. This paper addresses this issue by first analyzing the mechanisms by which PV power stations generate harmonics. Then, based on international standards for harmonic monitoring, it evaluates harmonic and interharmonic distortions of PV power stations under different operating conditions. Finally, a comprehensive comparative analysis of harmonic testing data from different grid-connected inverters in a PV power station under various conditions is conducted. The results indicate that inverter harmonic and interharmonic levels are significantly dependent on power variations under changes in sunlight intensity, and in the presence of different voltage waveform distortions and different equivalent source impedance values.