The inverters used in photovoltaic power plants are industrial electronic devices that can cause harmonic pollution on electrical networks. For proper electrical energy quality, the reactive and distorting powers generated by these harmonics must be compensated. One solution for ensuring power compensation on electrical networks with photovoltaic backup coupling is the three-phase shunt active filter (SAF). Effective pollution control is synonymous with effective power compensation, which requires proper sizing of the active filter. Indeed, the quality of the SAF lies in the quality of the control of the switches in the inverter that constitutes it. This work presents a simulation study of harmonic disturbances on photovoltaic-coupled low voltage (LV), medium-voltage (MV) and high-voltage (HV) electrical networks, as well as solutions for compensating for disturbances related to the presence of these harmonics on electrical networks. The results show that connecting photovoltaic power plants to existing electrical networks creates harmonic disturbances on the latter. Observation of the waveforms and harmonic spectra of the currents shows the presence of odd harmonics on the electrical networks studied. This pollution is significant in LV and MV networks, but becomes almost nonexistent in HV networks. Waveforms are more distorted in LV than in MV and HV. In LV, the Total Harmonic Distortion (THD) drops from 7% to 6.3% after applying the SAF, while in MV it drops from 0.02% to 0.01% after applying the SAF.