This thesis addresses the design of a hot water power plant for heating low thermal mass buildings, with a special emphasis on the optimization and dimensioning of the thermal storage buffer tank to ensure thermal energy storage and system stability. The thesis thoroughly explores the technical aspects of design and calculations for all key system components. The introductory section of the thesis describes theoretical concepts related to the operation of hot water power plants and the principles of thermal energy storage systems. Special focus is placed on different methods of thermal energy storage. Following the theoretical introduction, the thesis focuses on a detailed description of the main components of the hot water power plant and the calculations necessary for the dimensioning of each component. The final part of the thesis includes an analysis of the integration of a photovoltaic system into the power plant, where the photovoltaic panels were dimensioned according to local insolation conditions. Additionally, the savings achieved after the implementation of the photovoltaic power plant are presented. At the end of the thesis, all technical specifications of the individual components are provided, as well as a hydraulic system diagram and a 3D visualization of the system connections. These technical illustrations provide a better overview of the system's operation and facilitate understanding of the complex processes within the hot water power plant. The thesis offers a detailed technical insight into the design and optimization of modern energy systems for heating low thermal mass buildings.