Passive PV module cooling under free convection through vortex generators

Abstract

High operating temperatures have a negative impact on photovoltaic (PV) modules. Hence, lowering the temperature of commercial crystalline silicon modules during their operation becomes increasingly interesting, as it increases the system's energy yield and prolongs the module's lifespan. In this work, we experimentally and numerically investigated a potentially cost-effective passive cooling method for PV modules, using vortex generators (VGs) optimised for free convection conditions (in the absence of wind). The VGs are attached to the rear surface of the module and arranged in an array. Infrared thermography was employed to assess the cooling ability of the VGs with different spacing. It is found that the thermally non-conductive VGs can reduce the operating temperatures of a module by up to 2 °C under free convection and by 3 °C with the use of conductive materials. To better understand the flow behaviour around the VGs, computational fluid dynamics simulations were undertaken, along with particle image velocimetry (PIV) measurements. The VG-induced mixing in the boundary layer is responsible for enhancing the convective flux on the rear module surface. We observed both that the formation of vortices is strongly dependent on the aerodynamic shape of the VG and that the placement of the VGs is crucial.