Impact of Rooftop PV on Transformer loading and Life: A Real-time Metrological Data Driven Study

Abstract

Solar PV plant integration into the grid boosts green energy generation, but it may also impact the grid supply power quality, transformer loading, and lifespan. This study develops a mathematical model that relates meteorological data (solar intensity and temperature) to the transformer loading and life through their impact on PV plant power output and grid supply power quality parameters (total harmonic distortion of current, \({\text{TH}}{\text{D}}_{\text{i}}\) & power factor, PF). The real-time data collection is done from a 33 kV grid-connected 100 kWp rooftop PV plant and its analysis show that during the peak summer season, the rise in PV module temperature (average: 11.89°C) causes a 5.8% increase in transformer loading. During the peak winter season, the low solar intensity becomes detrimental to \({\text{TH}}{\text{D}}_{\text{i}}\). The generation of high \({\text{TH}}{\text{D}}_{\text{i}}\) in winter (average: 32.26%), causes an increase in transformer loading up to 5.1%. The plant’s power factor (PF) also contributes to an increase in transformer loading; a reduction in PF to 0.81 (lagging) leads to an expected 10.10% increase in transformer loading. These small increases in transformer loading may collectively reduce the transformer life.