Solar thermal system design is an energy-efficient solution for producing hot water and thermal energy using renewable resources. The design process evaluates building demand, available roof or ground area, and solar orientation. Solar collectors are used for domestic hot water preparation, heating support, and swimming pool heating. These systems are suitable for private houses, apartment buildings, hotels, sports facilities, and industrial sites. Designs may include flat-plate or vacuum tube collectors, storage tanks, and control systems. Proper integration with existing heating and hot water systems is a key aspect of system performance. A well-designed system ensures high efficiency and long service life. Solar thermal systems significantly reduce energy consumption and operating costs. This solution supports sustainable and environmentally responsible building operation.