Performance enhancement of a PCM-cooled photovoltaic panel using intermittent ultrasonic piezoelectric cool-mist generation: An experimental study

• Hybrid PCM–fog cooling system reduces PV temperature and improves stability. • Pulsed fogging prevents vapor saturation and enhances evaporative cooling. • Long-OFF duty cycles yield superior temperature control and thermal uniformity. • Pulsed cooling reduces PV hot spots and improves surface temperature uniformity. • Optimal fog–PCM interaction increases net power output and system efficiency. In this study, the performance of a pulsed cold fog cooling system for a photovoltaic panel equipped with PCM was experimentally evaluated. The experiments were conducted in three time cycles of 60, 120, and 240 seconds and with different ON/OFF patterns, and the results were compared with two reference modes: no fog and continuous fog. The findings showed that pulsed cold fog is able to reduce the panel temperature by more than 10 degrees compared to the no fog mode and in many cases provides better performance than continuous fog, because long OFF periods allow for effective ventilation and increased evaporation efficiency. Patterns such as 12ON48OFF and 48ON192OFF produced the lowest stable temperature and the best temperature uniformity. The electrical parameters were also directly affected by the thermal improvement, such that appropriate pulse patterns increased the voltage, useful power, and system efficiency compared to both reference modes. The best performance was achieved with patterns with short ON and long OFF, which prevented moisture saturation and reduced the energy consumption of the piezoelectrics. Overall, the results show that pulsed cold fog can be a cost-effective and efficient solution for improving the thermal and electrical performance of solar panels.