Enhancing thermoelectric generation: Integrating passive radiative cooling and concentrated solar heating with consideration of parasitic heat conduction

Thermoelectric generators (TEGs) integrated with solar energy and radiative cooling offer a promising approach for generating power. Concentrated solar energy enhances generation by increasing the solar flux density. However, the relationship between thermoelectric generation and concentration ratio remains not well understood. In this study, the finite element method is employed to investigate the temperature difference across TEGs and the change in generation performance with varying concentration ratios. The results show that due to the mismatch among cooling, heating, and parasitic heat conduction powers, the optimal power generation does not occur at the maximum concentration ratio. As the concentration ratio increases, the temperature difference across the single TEG and its output power initially increase and then decrease. To further improve the power generation performance at high concentration ratios, this study introduces TEG stacking strategy to enhance waste heat recovery by increasing thermal resistance. Outdoor experiments with self-made solar absorptive coating and radiative cooling coating validate this approach, achieving a temperature difference of 64.17 °C and a power density of 135.57 W m⁻² by stacking three TEGs, outperforming a single TEG by over three times. This study offers a potential method to continuously power remote off-grid communities and low-power devices.