The study compares performance predictions from blade element momentum theory, CFD methods, and experimental results for a 2.5 MW horizontal wind turbine across various wind speeds. The results indicate that CFD or in complex flow conditions, although blade element momentum theory remains useful during the initial design stages. The analysis also underscores the influence of wind speed and shear stress transport on performance metrics such as turbine power output and flow characteristics. Despite certain modelling simplifications, such as the omission of detailed blade tip geometryies, the findings suggest that both numerical methods exhibit trends consistent with the field experimental data. The study highlights the importance of detailed simulations for optimizing wind turbine performance and outlines future research focused on noise reduction and its impact on biodiversity.