The task of this diploma thesis is to carry out an analysis of the economic profitability of building a solar power plant on a selected test example with regard to the current methods of incentives that have been applied in Croatia and the new incentive proposal under the new Law on Renewable Energy Sources and High-Efficiency Cogeneration, and their comparison. In the introductory part, an overview of the development of solar energy in the EU and the Republic of Croatia is given, as well as the directions for the development of this sector in the future. Basic parts, characteristics of operation and production of solar power plants and methods of their connection to the power grid are described. The chronology of state incentives for the FN system of the Republic of Croatia is given, the tariff system for the production of electricity from RES and cogeneration is described, as well as the new law on RES and K. Models of incentives and self-sufficiency are described with examples from other EU countries, as well as the possibilities of obtaining investment incentives. Next, the basic economic parameters used in cost-effectiveness analyzes are described. An Excel model was created for the analysis of annual electricity production according to data on insolation for the Split location, as well as a model for analysis of consumption according to the available consumption data from HEP ODS. The income budget was made in two variants, according to the old and new law, and investment costs and maintenance costs are the same for both cases. The analysis of the economic profitability of building a solar power plant is explained in detail for both cases and accompanied by an example from an excel model. From the analyzes carried out, the conclusion is that the old model of the Law on the Tariff System, which was adopted in 2007, worked in the hands of producers, where it was possible to quickly return the invested capital and make a significant profit, but in the long term, the incentive prices were unrealistic. By changing the law in 2016, following the model of other European countries, a model was created in which there is no direct sale of energy to the grid, but a kind of compensation is carried out, where after settling own consumption, only surpluses are sold to the grid at specially defined market prices. This model is more realistic in the long run, and the analysis showed that it is also profitable for the investor, only with less profit than the previous model. In the future, when we expect a lower price of equipment and an increase in the retail price of electricity, the profitability parameters will be better, and this model will satisfy both manufacturers and suppliers.