A photothermal synergistic energy recovery model and simulation for underwater vehicles

• Established a coupled PV–PCM–TEG hybrid framework for underwater power generation. • Revealed a three-stage depth-dependent transition in hybrid energy conversion behavior. • Achieved full-depth power continuity with DCF > 0.9 across 0–1200 m depth range. • Delivered 5.1 times higher recoverable energy per cycle than single-source systems. • Demonstrated tunable power profiles via PCM phase-transition temperature control. This study presents an integrated photovoltaic–phase change material–thermoelectric generator (PV–PCM–TEG) hybrid system designed for long-endurance underwater gliders performing cyclic dive–ascent missions. The system couples solar harvesting, latent-heat buffering, and thermoelectric conversion to maintain continuous power generation across varying depths. A coupled thermal–electrical model incorporating realistic irradiance attenuation and ocean temperature stratification reveals a three-stage energy evolution: a high-power surface zone (81.1 W m⁻²), a thermocline transition with polarity reversal, and a deep-sea steady regime (2.5–7.5 W m⁻²). Over a four-hour cycle, the hybrid system generates 8.53 Wh of recoverable electrical energy—5.1 times the consumption of a conventional glider—thus significantly extending mission endurance. Depth-Coupling Factor (DCF) analysis shows that the configuration maintains power output above operational thresholds across 92 % of the total depth range, demonstrating strong adaptability and reliability. These results confirm that coupling photovoltaic and thermoelectric mechanisms via latent-heat buffering enables robust, full-depth energy harvesting, offering a pathway toward self-sustaining, high-efficiency underwater missions.