Waveform distortions of voltages and currents are a recurring concern in the context of Photovoltaic (PV) systems. Reports exist where large PV systems shut down because of increasingly large grid voltage distortions. Due to the complexity of the system (PV installation and grid) it is difficult to discern whether the PV system generates or just amplifies a distortion. Frequencies observed in these events are various, come from both harmonic and interharmonic regimes, and call for a frequency-sensitive analysis. However, studies that investigate PV systems in the context of waveform distortions often focus on total distortion values. As a result, reports on the impact of PV installations on the Total Harmonic Voltage Distortion (THD V ) are inconsistent. Increasing, decreasing, and negligible effects on THD V are observed. We investigate the impact of a PV system in the field and keep a spectral perspective as opposed to aggregated values such as THD V . Due to repeated shut-downs and power-ups of the system over the course of two days, we ensure to attribute observed effects to the system under investigation (and not other loads in the grid). We observe that voltage waveform distortions in the range from 700 Hz to 1250 Hz are reduced whenever the PV-system is connected to the grid, while distortions at other frequencies are increased or not affected. The impact of the PV system on voltage waveform distortions is frequency sensitive, and thus aggregated total distortion values are not a suitable measure in this context. • In-field investigation of a commercial photovoltaic system in high spectral resolution • Measurement scenario including repeated shut-downs and power-ups of the system • Total distortion values are an insufficient measure and lead to contradictory results • Reduction or increase of grid voltage waveform distortions depending on frequency.
Förstner et al. (Sun,) studied this question.