Thermal regulation of PV façade integrated with thin-film solar cells through a naturally ventilated open air channel

Abstract

Thermal regulation of photovoltaic façade through passive air channel provides a cost effective measure for improving solar to electrical energy conversion efficiency. This study presents a 2D numerical investigation of the fluid flow and heat transfer characteristics of natural convection driven by buoyancy force inside the passive cooling air channel created by two vertical parallel walls. One wall is heated by absorbed heat by photovoltaic (PV) cells from solar radiation. Numerical solutions for open and closed channel are obtained for the channel of 1.05 m in height and 0.16 m in width, respectively. The natural convective cooling effect on the PV cells for different ventilation strategies were examined considering the surface temperature of PV panels. It is found that the maximum surface temperature reaches 57.1 o C for closed channel, 49.1 o C for opened channel. Opened channel behind the PV panel is an economic way of heat releasing for the benefit of PV power generation. However, other issues such as noise control and cleaning difficulty may also be encountered by façade designers. At the same time, understanding the mechanisms involved in the fluid flow and heat transfer in the channel back the PV panel through examining the pressure distribution along the cavity is required and equally important for the design improvements of PV façade especially for the design of the air channel entrance to lower its pressure drop.