Combined solar concentration and carbon nanotube absorber for high performance solar thermoelectric generators

Highlights: • A high performance solar thermoelectric generator system is proposed. • CNT film with high solar absorptance is successfully fabricated on the TE modules. • Thermoelctric efficiency keeps increasing with solar concentrating ratio. • Interdependent terms regarding to the efficiency of STEG are analyzed. • Optimal solar concentrating ratio which offer maximum system efficiency is found. -- Abstract: Solar thermoelectric generators (STEGs) is one of the most important technologies for solar energy conversion. However, the inefficiency due to coupling constraints such like low working temperature and dimensionless figure of merit of the thermoelectric materials, also known as material's ZT value, has been hampering the development of STEGs for a time. Here we demonstrate a high performance STEG system combined with solar concentrators and carbon nanotubes (CNTs) absorber, which can greatly improve the solar-thermal conversion process. The proposed STEG system enables a peak efficiency of 4.3% with solar concentration of 78, and a maximum power of 11.2 W at 106× suns. The enhanced efficiency is ensured by the optimized system thermodynamics due to the combination of solar concentration devices and CNT based solar absorber. Our design provides a universal prototype of solar thermal energy recovery system for distributed energy harvesting and deep-space explorations.