High-performance terrestrial solar thermoelectric generators without optical concentration for residential and commercial rooftops

•A record efficient STEGs is designed, realized, characterized, studied and tested.•The theoretical models and the thermodynamics process are established and analyzed.•The relevant parameters influencing its performance have been discussed and optimized.•Small-scale solar thermoelectric applications has been developed.•The directions for future research work STEG have been discussed. Solar thermoelectric generator (STEG) systems are attractive because they can convert solar heat directly into electricity via solid-state thermoelectric generators. Nevertheless, its low energy conversion efficiency has prevented it from wide-scale implementation and commercialization. To date, the best experimental efficiency for STEG without concentrated is 4.6%, and only testing single thermoelectric unicouple within a specific application deployment context. In this paper, a mathematical model containing various heat losses ignored by previous studies are developed and validated to confirm the possibility of improved STEG performance. We developed a high-performance solar thermoelectric hybrid device composed of heat pipe evacuated tubular collector, solar selective absorber, and TE modules by conducting a comprehensive optimization in terms of thermoelectric material, the optical and thermal efficiency of solar selective absorber, heat management and device integration. The experimental results show that the thermoelectric conversion efficiency of proposed device was enhanced significantly, it produced a peak electrical efficiency of 5.2%. And the residual solar energy is stored for either power generation or domestic used. The peak exergy efficiency of the system reached up to 7.17%. The efficiency is higher than the previously reported best value. We experimentally demonstrated the feasible of the scale application of solar thermoelectric generators. And the results indicated that STEG system is a promising alternative solar energy thermal utilization technology in the small scale co-generation applications.