This chapter provides an in-depth analysis of heat transfer mechanisms crucial for high-temperature solar thermal systems. It examines the principles of conduction, convection and radiation concerning their roles in the efficient absorption, transmission and conservation of solar energy. Emphasis is placed on the importance of material properties, such as thermal conductivity and specific heat capacity, which significantly influence the performance of solar collectors, receivers and thermal storage components. The discussion extends to the thermal characteristics and structural stability of widely used materials, including metals and advanced composites, under varying thermal conditions. A detailed comparison of different heat transfer fluids (HTFs) such as water/steam, thermal oil, molten salt and metal-based fluids is presented, highlighting their thermophysical properties and suitability for various operational temperatures. Furthermore, the chapter explores novel approaches to enhance system efficiency and reliability, including advanced thermal management technologies like phase change materials (PCMs), hybrid cooling systems and nanomaterial-based improvements. In conclusion, optimizing heat transfer through careful selection of materials, fluids and thermal strategies is paramount for the sustainable development and deployment of solar thermal energy technologies.