A 3D numerical model is developed to estimate and analyze the flow and performance parameters of solar updraft tower (SUT) plant. The effects of geometrical parameters, such as chimney height and collector roof angle are studied. A turbulent, renormalization group (RNG) k-epsilon model and discrete ordinates (DO) model is used to solve the governing equations. It is concluded that with an increase in collector roof angle, air velocity increases but air temperature decreases. There is 31% velocity enhancement when the chimney height is increased from 3 to 8 m. The overall, chimney and collector efficiencies and power output are estimated to be 0.00354%, 0.0465%, 81.4% and 0.255 W, respectively.