Flat plate solar air heaters present a low thermal efficiency to produce hot air to several applications, such as ambient heating and fruits and grains drying. In order to contour this problem, the use of longitudinal vortex generators has been becoming a viable solution, since the heat transfer between the solar air heater and the flowing air is enhanced; however, as the pressure drop also gets increased, punching a louver into the winglet acts to counteract this drawback. The present study aims to numerically analyze the influence that different winglet types, angles of attack, louver flap angles and Reynolds numbers have on the heat transfer enhancement and pressure loss characteristics. Results show that louvers in rectangular winglets, rather than delta winglets, have a greater potential of diminishing the pressure drop of the solar collector, and elevated louver flap angles contribute positively on the thermo-hydraulic performance for any Reynolds number, with a maximum thermal enhancement factor of 3.105.