Structure optimization of solar thermoelectric generator under nonuniform solar radiation

Solar thermoelectric generators (STEGs) offer a direct means of converting solar energy into electricity. Optimizing the thermoelectric leg structure represents a viable approach to enhance the thermoelectric performance of STEG. However, the utilization of concentrators often results in nonuniform solar radiation, and the optimization of thermoelectric leg structures under such conditions remains unexplored. To address this gap, this study presents a comprehensive investigation wherein a three-dimensional thermal-electric coupled model is established for STEGs operating under nonuniform radiation, with a specific focus on the structural optimization of thermoelectric legs under these circumstances. The results demonstrate the presence of a critical cross-sectional ratio that functions as a determinant of the potential benefits associated with nonuniform radiation. Notably, when the cross-sectional ratio exceeds this critical threshold, nonuniform radiation yields higher output power compared to uniform radiation. In the absence of material operating temperature, there exists an optimal ratio of cross-sectional ratio to height of 0.027 mm−1, which maximizes the output power of STEG. Moreover, with increasing height of thermoelectric leg, the output power exhibits slight variation within a margin of 1 %. Regardless of varying radiation conditions, the optimal structure remains consistent; however, the utilization of nonuniform solar radiation leads to a maximum relative reduction of 4.08 % in output power compared to uniform radiation. Furthermore, when considering material operating temperature, the optimal cross-sectional ratio under nonuniform radiation tends to be larger, consequently resulting in diminished thermoelectric performance. Additionally, as the level of radiation nonuniformity increases, the output power of STEG with optimal structure experiences a decline. The maximum reduction amounts to 20.72 % when compared to uniform radiation conditions. Overall, these findings provide valuable insights and guidance for the efficient and secure operation of STEGs.