15-Fold increase in solar thermoelectric generator performance

Summary

STEG output power enhancement strategiesA STEG generates electrical power when there’s a ΔT across its hot and cold sides. The generated power is expressed as38$${P}_{{STEG}}={\left({S}_{{TEG}}\varDelta T\right)}^{2}\frac{{R}_{L}}{{\left({R}_{L}+R\right)}^{2}}$$ (1) where \({S}_{{TEG}}\) is the effective Seebeck coefficient of the TEG, R is the total electrical resistance between the TEG terminals, and \({R}_{L}\) is the load resistance. For a given TE material, an effective way to increase \({P}_{{STEG}}\) is to enlarge the ΔT across it. To achieve this goal, proper spectral and thermal managements at the hot and cold sides are needed.To predict the effect of the hot- and cold-side thermal management, we conducted a numerical simulation of the heat transfer and thermoelectric effects for a STEG device (see Supplementary Note 1). Starting with a bare STEG attached with an ideal broadband solar absorber (BBA) and a regular metal heat dissipator, we investigated the enhancement of the STEG output power by reducing the inevitable thermal loss at the hot side and increasing the heat dissipation at the cold side (Fig. 1b). Assuming the hot-side thermal management minimizes the radiative loss and reduces the convective heat transfer coefficient by half. Similarly, we assume that the cold-side thermal management maximizes the radiative cooling and doubles the convective heat transfer coefficient. When the absorber converts solar energy to heat, part of the energy is lost due to hot-side radiation and convection. The rest is conducted through the STEG to the cold side, and this portion is utilized for power generation. Figure 1c shows the STEG peak output power for each case, and Fig. 1d shows the corresponding energy flow. The enhanced \({P}_{{STEG}}\) with thermal management is due to more thermal energy utilized by the STEG (represented by the blue bars). To have more thermal energy utilized by the STEG, the hot-side thermal loss needs to be minimized, while the cold-sid...