Abstract Small horizontal axis wind turbine rotors with composite airfoil rotor blades were designed and investigated in the present study in order to improve its performance in low wind speed and low Reynolds number (Re) conditions for standalone system. The geometrical and aerodynamic nature of a single airfoil small horizontal axis wind turbine blade curtails efficient energy harnessing of the rotor blade. The use of composite airfoil rotor blade improves energy production but imposes uncertainty in determining an optimal design angle of attack and the off design aerodynamic behaviour of the rotor. This research investigated the effects of two airfoils used at different sections in a composite blade and determined the blade’s optimal design angle of attack for maximum power generation. The wind turbine rotor blades were designed using blade element momentum (BEM) method and modelled by SolidWorks software. The SG6042 and SG6043 airfoils were used for the composite airfoil blades. Five wind turbines were designed with rotor blades of design angles of attack from 3° to 7°. The five wind turbine blades were simulated in computational fluid dynamics to determine the optimal design angle of attack. The composite airfoil wind turbine blade showed improved performance, whereas, the wind power generated ranged from 4966 W to 5258 W and rotor power coefficients ranged from 0.443 to 0.457. The blade with design angle of attack of 6° showed highest performance. Keywords: composite airfoil, lift-to-drag ratio, pressure coefficient, Reynolds number, design angle of attack.