This work presents a lightweight and minimally invasive cooling system design with forced water cooling, which can improve photovoltaic (PV) system performance by thoroughly reducing the temperature of its solar cells. This design is an improved version of traditional PV-thermal cooling systems that are bulky and mostly limited to land-based applications. Thermal and fluid flow analyses of this system have been presented to numerically assess output efficiency improvement with a commercial solar panel. The proposed serpentine cooling block structure has been optimized to maintain module efficiency better than Standard Testing Conditions (STC) under all conditions. For a 395 W commercial solar panel, an output power improvement of up to 49.4 W (14.29%) at an irradiance level of 1000 W/m2 at an ambient temperature of 35 °C has been achieved. The corresponding water pump operation and associated losses are limited to a maximum of 8.5 W/module. The impact of cooling system performance has also been evaluated for the region of Mangla Dam Lake, Pakistan, where an annual increase in electricity output of around 9.58% is foreseen. Consequently, this work is envisioned to provide guidance on increasing the efficiency of the PV system to those who would install it near water reservoirs. © 2020 Author(s).