Characteristics of heat dissipation from photovoltaic cells on the bottom wall of a horizontal cabinet to ambient natural convective air stream

This study proposes a model to investigate the behaviors of natural convective cooling of photovoltaic cells mounted discretely on the bottom wall of a horizontal cabinet. The effects of Rayleigh number (Ra), dimensionless length of cabinet (Cx), ratio of cabinet wall to air thermal conductivities (Kef), number of photovoltaic cells (N), emissivity of metal wall (εe), and emissivity of glass lens (εg) are explored. Furthermore, the importance of thermal interaction between air streams inside and outside the cabinet through conducting wall are examined. The numerical computation domain covers the cabinet and surrounding area, so that the temperature and velocity fields of the combined regions are solved simultaneously. Results show that temperature differences among the photovoltaic cells can be up to 28% for all the investigated cases when 106 ≦ Ra ≦ 108, 5 ≦ Cx ≦ 12.5, 4 ≦ N ≦ 10, 1000 ≦ Kef ≦ 6300, 0 ≦ εe ≦ 0.5 and 0 ≦ εg ≦ 0.94. The maximum difference in hot spot temperatures of photovoltaic cells is about 26% among the cases with various Kef. In addition, the temperatures are rather low for the situation without consideration of thermal interaction between the air streams inside and outside the cabinet. Therefore, without the consideration of the thermal interaction would cause serious under-prediction for the hot spot temperatures of photovoltaic cells in engineering applications.

► A model to investigate the natural convective cooling of photovoltaic cells mounted on bottom wall of a horizontal cabinet.
► The temperature and velocity fields of the cabinet and surrounding area are solved simultaneously.
► The temperature differences among the photovoltaic cells can be up to 28%.
► Without the consideration of the thermal interaction would cause serious under-prediction for the hot spot temperatures of photovoltaic cells.