Photovoltaic (PV) systems generally use the inverter to convert Direct Current (DC) power into Alternating Current (AC) power so that it can be combined with the utility grid system. The inverter may generate a disturbance in the frequency range between 9-150 kHz due to its frequency switching, which may degrade the power quality and affect the performance of other equipment connected to the system. In this manner, this paper presents an investigation of disturbance characteristics in the frequency between 9-150 kHz generated by an inverter of the PV system under fluctuated solar irradiance. This study explores the correlation between different solar irradiance with the disturbance generated by the inverter. Two types of the PV system are investigated, such as off-grid and on-grid system. The results show that a higher solar irradiance generates a higher disturbance. Furthermore, it is also shown that the off-grid system generates higher disturbance (7.6%-30.8% per 100W/m2) than the on-grid system (2.6%-14.12% per 100W/m2).