Preliminary experiment and performance evaluation of a terrestrial solar thermoelectric generators under fluctuant solar radiation

•The terrestrial solar thermoelectric system was built and test in typical days.•Changes of the performance of the system in practical situations are revealed.•The performances of the system and pure solar hot water system are compared.•It provides a valuable reference for the engineering design of system. The solar thermoelectric generator (STEG) is a promising alternative terrestrial solar power generation device due to its ability to utilize almost full solar spectrum. Many researches have been carried out to improve its efficiency. Some improved STEG has achieved remarkable efficiency in the laboratory. However, its performance in practical situations has been few studied, which limits its practical applications. In this work, the experimental investigation and performance evaluation of the terrestrial STEG system in typical days in East China are presented. Detailed changes in efficiencies and output power of the system are revealed. The results show that the performance of the system changes with the environment. The system can obtain the highest one-day electrical efficiency of 3.22% at 12:00 in the noon and thermal efficiency of 53% at 15:00 in the afternoon. The influences of solar irradiance, cooling water temperature and water cooling quality are discussed. The optimization methods of the system running in real environment are discussed and optimized to improve the average efficiency in the long run. The performances of this system and pure solar water heating system without TE modules are compared and the details are presented. The hybrid system has a higher comprehensive performance and lower thermal performance than the pure solar water heating system. This work provides a valuable reference for the design and optimization of STEG running in real environment.