A numerical examination on the use of phase change materials to improve the sun-tracking photovoltaic panels' performance

Abstract

The power generation of a photovoltaic (PV) panel is inherently affected by the amount of solar radiation striking the panel and the PV temperature. Tracking PV panels reach higher temperature than fixed panels due to more received radiation. Phase change materials (PCMs) are widely used as a passive method for cooling fixed PV panels. The melting dynamics of the PCM is very different during tracking compared to previous research carried out on fixed panels due to the changing orientation. A tracking PV-PCM system is numerically modeled in this research, and the temperature distribution and convection in the PCM are analyzed. The numerical results are presented as temperature-time curves for several different positions inside the PCM container, liquid fraction and streamlines in melted PCM, and isothermal curves. The temperature variation shows that the temperature of solid PCM increases rapidly in the initial time, reaching the melting temperature. The PCM changes from the solid phase to the liquid phase at a constant temperature. After complete melting, the PCM temperature increases over time. The PCM temperature changes were compared at two different distances from the photovoltaic panel. The streamlines show that the PCM starts to melt near the heated wall at the container's top corner. The melted PCM expands toward the down of the container due to vortex circulation created in the molten material. It is observed that the increase in PV panel temperature between 1.5 and 7 h is only 5.3 K, showing that using PCM is an effective method for absorbing heat from the PV panels during melting. Results show that the temperature of PV panel with PCM is on average 6.9 K lower than that without PCM.