•A novel PCM-PV/T collector with PCM connected in parallel is proposed.•A numerical model for the novel PCM-PV/T system is established and validated.•Sensitivity analysis of key operational and structural parameters is conducted.•The start time and duration of phase transition process are revealed and analyzed.•Details of melting ratio and heat gain of PCM are displayed and discussed. Applying PCM to the photovoltaic/thermal (PV/T) system can adjust the operating temperature of the photovoltaic cell and further enhance system efficiency. Hence, in the present study, a novel PV/T-PCM collector by connecting the PCM with the heat-absorbing plate in parallel is first proposed. Then, the dynamic model of the PV/T-PCM system is established and verified. Finally, the sensitivity analysis is performed on key parameters, including the water mass flow rate, water tank volume, PCM thickness, and phase transition temperature. The results show that raising the water mass flow rate improves electrical gain, total heat gain, and total system efficiency; however, their change gradient is all inconspicuous as the water mass flow rate is greater than 0.02 L/s. As the water tank volume expands from 75 L to 105 L, electrical gain, total heat gain, and total system efficiency are improved. Thickening the PCM can promote the electrical gain, while the total system efficiency and total heat gain will increase slightly at first and then decrease. The best thickness is 0.015 m. When the phase transition temperature increases from 40 ℃ to 50 ℃, the total system efficiency and total heat gain decline, but the electrical gain decreases insignificantly. The changes of the above four parameters all affect the complete melting ratio of PCM as well as the phase transition start time on the entrance side and exit side of the collector.