This paper introduces the configuration of main portions of concentrated solar thermal power plants (CSTPPs). This configuration play a very important role in the operation of these plants. It also proposes for these plants a new compact mathematical modeling which has an advantage that the expressions of most plant portions are free of any complex or thermal details that describe the conventional model [4] and [5]. Depending on that mathematical modeling of CSTPPs components, a flow chart is designed to determine the power flow of each portion and the net output power of the plant. MATLAB program that has more availability in design equations, inputs and outputs editing will be coded and executed. SAM program will also be used to obtain the same results of the CSTPPs obtained by using MATLAP program. The results of both programs are very close showing that the determination of the power flow of each portion and the net output power of the plant is accurate with high confidence degree.