This research addresses the challenge of elevated temperatures impacting the performance of photovoltaic (PV) panels, considering both the dimensions of the cooling tube and the flow of water. A comprehensive analysis of various water flow rates is conducted using three tubes (tube 1, tube 2, and tube 3) with cross-sections of 100.27, 148.27, and 202.27 mm2 and 15, 11, and 9 loops, respectively. The numerical results reveal a significant 41.66% reduction in PV cell temperature, decreasing from 60 °C to 35 °C using tube 3 at a flow rate of 7.5 L/min, reflecting high electrical performance and efficiency. Meanwhile, at a flow rate of 1.5 L/min, tube 1 delivers optimum hot water at the outlet with a temperature of 55.6 °C. The proposed design significantly contributes to PV cell efficiency, emphasizing the impact of cooling tube dimensions on the overall efficiency of the PV/T system. This study introduces an innovative approach using a flat oval tube to minimize temperature elevation and simultaneously generate hot water. The innovative PV/T system demonstrates potential advancements in thermal management and lays the foundations for future sustainable energy applications.