Parabolic troughs are one of the low cost solar electric power options available today and havernsignificant potential for further cost reduction. Parabolic trough power plants use concentratedrnsunlight, in place of fossil fuels, to provide the thermal energy required to drive a conventionalrnpower plant. These plants use a large field of parabolic trough collectors which track the sunrnduring the day and concentrate the solar radiation on a receiver tube located at the focus of thernparabolic shaped mirrors. A heat transfer fluid passes through the receiver and is heated torntemperatures required to generate steam and drive a conventional Rankine cycle steam powerrnplant.rnIn this thesis paper model of a parabolic trough power plant, taking into consideration therndifferent losses associated with collection of the solar irradiance and other thermal losses isrnpresented. MATLAB software is used to model the power plant at reference state and TRNSYSrnsoftware is used to simulate the performance of the model at off design weather conditions.rnMATLAB modeling of the power plant is used to find the different reference values which arernused as inputs for the TRNSYS modeling and simulation of the power plant. The referencernvalues include the solar field area, the heat transfer fluid (HTF) and steam/water mass flow rates,rnoverall heat transfer coefficients of the different heat exchangers, etc.rnThe TRNSYS modeling and simulation are used to determine the net power, initial steamrntemperature, the inlet and outlet heat transfer fluid temperatures out of the solar field and steamrnand HTF mass flow rates in hourly basis for representative days of year 2001.rnThe cost and financial analysis is made for the power plant. Solar Advisor Model is used to makernthis analysis under Addis Ababa weather condition. This analysis is used to determine therndifferent costs associated with the power plant. The cash flow for the 30 years of operation of thernpower plant is also shown.