The final paper describes the basic parts of solar power plants (SP), the method of connection to the power grid, the basic structure of the costs of building solar power plants, and the possibilities of modeling and analyzing the cost-effectiveness of investments in the SAM NREL program package. The basic parts describe the photovoltaic cell, photovoltaic module and DC-AC inverter. This final paper also describes the basic economic parameters used for profitability analysis and the basic cost structure of solar power plant construction. An analysis of the profitability of the investment in the program package SAM NREL was also presented, which offers us the possibility of modeling the system and, with the input of certain parameters, to obtain output data that will give the calculation of the invested and obtained money with the project profitability.