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• Rectangular wing VGs attached to PV modules tested for outdoor passive cooling. • Observations revealed wind speed and directional-dependent cooling of the VGs. • Dual cooling mechanisms, vortex generation and heatsinking, are identified. • Aluminium VGs exhibit a superior heatsink effect, achieving up to 2.5 °C cooling. • VGs only covers 12.5% of the module surface, using minimal amount of material. Reducing the operation temperature of photovoltaic (PV) modules will allow prolonging their service time and energy output. This work investigated a passive PV module cooling technique by attaching vortex generators (VGs) on the rear surface of PV modules. The rectangular wing VGs of size 2 × 3 cm, are made from aluminium sheet (Al VG) or 3D printed thermally conductive polymer (Poly VG). After ten months of data collection on an open rack system, we have gained insight into the wind speed- and direction-dependent performance of the Al and Poly VGs. The pronounced difference in thermal conductivity of the two materials helps distinguish cooling due to vortex generation, predominant at low wind speeds, from the heat sink effect, prevalent at higher wind speeds. Despite being optimised for free convection, both VGs demonstrated 1.5 °C of cooling under low wind and high irradiance, while Al VGs provided 2.5 °C of cooling under high module temperature and windy scenarios. Both VGs exhibit equivalent performance with south and west winds, indicating the dominance of the vortex generation mechanism. The module equipped with VGs exhibited an increase in convective heat transfer coefficient as evaluated by the thermal balance model. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]