Voltage harmonic effect of a large-scale solar PV plant on high-voltage transmission network

Photovoltaic solar energy is one of the most cost-effective renewable technologies, driving significant global expansion. In Spain, renewable energy policies and environmental awareness have led to a rapid increase in photovoltaic plant installations. However, this growth poses challenges for power quality, particularly due to harmonic emissions that can affect grid stability and efficiency. This study analyses voltage harmonics in a 35 MW photovoltaic solar farm in south-east Spain, comparing harmonic levels before and after commissioning. Statistical analysis of harmonic percentiles and their relative variations reveals specific frequencies with significant deviations, potentially impacting grid stability. A categorisation of harmonics based on their response to the plant’s operation is provided, highlighting those with extreme or irregular behaviour. These findings enhance the understanding of the effect of photovoltaic systems on voltage harmonics and offer guidance for mitigating harmonic emissions in future installations.