摘要： High ambient temperature and excessive solar radiation, especially in Upper Egypt, are essential factors in photovoltaic (PV) panel overheating, which in turn reduce its efficiency in such regions. Therefore, this study aims to develop a cooling system for the proposed thin-film PV panel installed in a harsh climate region in Qena City in Upper Egypt to obtain practically reasonable electrical efficiency. To achieve this target, three different cooling systems and operating modes were investigated: open-loop water-based cooling system, closed-loop water-based cooling system with free-convection air-cooled heat exchanger, and closed-loop water-based cooling system with forced-convection air-cooled heat exchanger using a DC fan. All these systems were supplemented with a fourth operating mode without cooling, i.e., normal conditions. The PV panel efficiency was experimentally investigated using the proposed cooling systems, and the experimental results demonstrated that without cooling, the daily average efficiency reached only approximately 6.2%, whereas it increased to 11.3% when the open-loop system was used. However, the daily average efficiency reached 8.5% using the closed-loop free-convection cooling system, and it reached 10.5% when the closed-loop forced-convection cooling system was used. Therefore, these cooling systems are highly recommended for application as effective techniques to increase the PV panel performance. The entire experimental data were obtained during a 10-h period from 7:00 a.m. to 5:00p.m.