Small-scale horizontal axis wind turbines (SSHAWT) have recently gained more interest due to fuel shortages and environmental issues. Generally, they are installed close to the ground in the wind boundary layer, where the velocity is relatively small. This study aims to evaluate the performance of a commercial SSHAWT and to modify rotor design based on wind velocity in the field. The experimental measurements are performed to examine a commercial 1.5 m radius rotor of 1 kW SSHAWT, which was designed at a rated velocity of about 8 m/s. The CFD calculations are performed as well to understand flow characteristics and to verify the experimental measurements. In the experimental procedure, the test of the wind turbine with a permanent magnet synchronous generator showed that at a wind velocity of 5 and 6 m/s, the highest generated power is 163.9 and 306 W corresponding to power coefficients of 0.255 and 0.28 when AC voltage of the generator is 24.4 and 37.76 V, the DC voltage after rectified 22 and 34 V, and the load current 7.45 and 9 A, respectively. Then the available wind velocity was measured in the field, and the average velocity was 4 m/s. Therefore, a more appropriate rotor is designed based on field velocity. The CFD calculations are used to test the new rotor. The results clarify that for the new rotor, the maximum blade’s power coefficient is enhanced by more than 60 % compared to the commercial rotor