This paper intended to investigate the performance of Copper Indium Gallium Selenide (CIGS) based Photovoltaic Thermal (PV/T) water collector under different operating condition. A CIGS photovoltaic with nominal power 65 W combined with an unglazed flat plate solar thermal water collector with effective area of 2 m was investigated. The performance was tested under different mass flow rates of flowing water which are 0.005 kg/s, 0.020 kg/s and 0.030 kg/s. For the mass flow rate of 0.030 kg/s, data was taken at different Peak Sun Hour (PSH) condition from 4.2 to 5.7. It was found that both electrical and thermal efficiency increased when the mass flow rate increased. Both electrical and thermal performance increased at the higher mass flow rate with the most efficient flow rate was 0.030 kg/s. The highest electrical and thermal efficiency was 4 and 23 respectively. In addition, when PSH increased, the electrical and thermal efficiency increased. However, at the PSH of 5.7 both efficiency slightly decreased. Further study on higher mass flow rate is necessary as the performance is not always proportional with mass flow rate. In this paper the value of the PSH was only limited to 4 points, which need to be further investigated for more values to clarify the correlation with the PV/T performance. © 2018 The Authors, published by EDP Sciences.