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HALE UAV needs solar energy to maintain its flight in the day and night. The solar panel located on the upper surface may potentially affect aerodynamic characteristics of the HALE wing. The solar panel generates a heat resulted from solar radiation absorption and surface roughness which becomes parameters to be studied. To identify the phenomena of interaction of flow motion and the heat as well as the roughness, dimensionless numbers such as Reynolds Number (Re), Nusselt Number (Nu), and geometry reference (Ks/C) are used. The simulations for flows at the numbers are conducted using CFD method based on the solution of RANS equations. As a result, the heat transfer gives significant change in flow density near the surface which causes buoyancy effect and the change of flow velocity profile, while the roughness influences the flow characteristics disturbing the flow to become turbulent. They increase aerodynamic drag of 2.6 % and aerodynamic efficiency in the amount of 5%.