Stabilizing all-day solar-radiative thermoelectric generation by reconfigurable thermal switching and dual phase-change storage

Autonomous off-grid electronics, from IoT sensors to remote monitors, require stable, low-maintenance solid-state power supplies, yet photovoltaic (PV) generation remains intrinsically intermittent. Solar-absorber/radiative-cooling thermoelectric generators (SA/RC-TEGs) can harvest solar and PV waste heat, but existing designs use static, back-leaking thermal links and hot-side-only phase-change buffering, causing rapid collapse of the TEG temperature difference (ΔT_TEG), severe day-night asymmetry, and limited output. Here we propose a thermal-switch-dual-PCM-radiative TEG (TS-DP-RT; PCM: phase-change material) that couples reconfigurable thermal routing with synergistic latent-heat storage. We developed a liquid-metal cavity TS (ON/OFF conductance ratio 84.4, zero holding power) that conducts by day to charge the hot-side PCM and drive the TEG, then isolates the hot reservoir at night to route stored heat through the TEG, while a radiatively recharged cold-side PCM buffers daytime warming. The TS retains >94% of its initial switching contrast over 100 cycles, showing high durability for practical adoption. TS-DP-RT delivers a mean power density of 46.27 W m⁻², 90% higher than the SA/RC-TEG baseline and exceeding literature values, with a stability figure of merit of 1.63 versus 0.87 for the baseline. Parametric and climate/seasonal studies yield design rules for TS design, PCM transition temperatures, geometry, insulation, and TEG stacking, showing robust hot-side PCM selection but climate-dependent cold-side PCM requirements. With concentrated PV waste heat and a 4-TEG stack, peak and mean power densities reach 487.26 and 154.73 W m⁻². Efficiency and cost analyses were also conducted. Overall, dynamic thermal switching with dual-PCM storage stabilizes off-grid thermoelectric generation.