The task of this final paper is to conduct a cost-effectiveness analysis of the construction of a solar power plant on a selected example, taking into account the new Act on Renewable Energy Sources and High-efficiency Cogeneration. The first part describes the technical potential of solar energy required for the operation of photovoltaic systems and the occurrence of the photovoltaic effect that is the basis for the production of solar energy. Then, photovoltaic systems are described, from the history of solar cells, through their types to the way they can be connected to the electricity grid, and an overview of technologies on which the future of solar energy use should be based is given. The second part analyzes the economic profitability of building a solar power plant using a model made in Excel that takes into account the insolation of the location, the possibility of tilting the module, the characteristics of the module and household electricity consumption to ensure maximum return on investment.