This study denotes an effective design for thermal regulating by integrating the water-cooling system on photovoltaic (PV) panel. The efficiency of the PV module will reduce the increasing temperature on the panel. Thus, the focus of this study is to improve the efficiency of the PV module by maintaining a low operating temperature. A modification on the rear part of the PV panel is executed by integrating the water-cooling system by using copper pipe. This study is conducted to compare the effects of the PV panel when it is tested in different circumstances, such as with and without water-cooling system as well as a variation of water flow rates at constant solar irradiance. Comparative analyses are performed by conducting IV and PV curve as well as temperature test where both tests take these different conditions into account. The study exhibits that the utilisation of water-cooling system will result to a reduced rear temperature of the PV panel. The efficiency of the PV panel has also experienced an increase of 3% for 300 l/h flow rates compared to the one without water-cooling system. The increase of flow rates of the water-cooling system will reduce the rear temperature of the PV panel. In other words, a more massive reduction of temperature on the PV panel with 16 C is detected when the water-cooling system is utilised up to 300 l/h flow rates in 60 minutes duration at 350 W/m 2 solar irradiance.