The control of large scale grid-tied photovoltaic rooftop systems to avoid the power factor charge

Large scale grid-tied photovoltaic (PV) rooftop systems are encouraged to install in many commercial buildings with the aim to saving the electricity energy bills. However, the support from PV system normally reduces only real power consumption while the use of reactive power is unchanged. In consequent, the power factor at the point of common coupling (PCC) may drop below the utility's prescribed value, causing the increase of power factor charge in the energy bill. The power factor correction by controlling reactive power supplied by PV rooftop system is presented in this work. The performances of this proposed control method are examined based on time-sweep load flow calculations on DIgSILENT PowerFactory software. The simulation results show that the reactive power compensation by PV interfaced converter, with smart control algorithm, can improve the power factor at the PCC effectively, without adding new compensation devices.