Under the action of waves, a small unmanned surface vehicle (USV) will experience continuous oscillation, significantly impacting its photovoltaic power generation system. This paper proposes a USV photovoltaic power generation simulation model, and the efficiency of photovoltaic MPPT control under wave action is studied. A simulation model for solar irradiance on solar panels of USV under wave action is established based on CFD and solar irradiation models. The dynamic changes in irradiance of USV solar panels under typical wave conditions are analyzed. The MPPT efficiency of USV photovoltaic power generation devices under continuously changing irradiance conditions is studied on this basis. The simulation research results indicate that waves and solar altitude angles significantly impact the instantaneous irradiation energy of USV photovoltaic devices. However, the impact of waves on the average irradiance is relatively tiny. The sustained oscillation of irradiance poses certain requirements for the Maximum Power Point Tracking (MPPT) control frequency of USV photovoltaic systems; a disturbance control frequency of no less than 50 Hz is proposed.

The application of ocean thermal energy conversion is an effective method to extend underwater vehicles’ running times and operating ranges, and the solid–liquid phase transition of the phase change material (PCM) in the heat exchanger is a key process for underwater vehicles to collect ocean thermal energy. This study proposes a heat exchanger structure for a small-size thermal energy power generation device and establishes the heat transfer model for the heat exchanger. Simulations were conducted considering convective heat transfer, and the obtained results demonstrated the feasibility of the designed structure. A prototype of the heat exchanger was developed, and physical experiments were conducted to validate the performance of the prototype. The results show that the melting process of the heat exchanger can be completed within 6 to 12 h, the solidification process can be completed within 3 to 7 h, and the heat transfer time decreases with the increase in temperature difference, verifying the compatibility with the underwater vehicles’ working patterns. Moreover, the heat exchanger could theoretically extend their lifetime. The results can provide a reference for the structural design and optimization of the heat exchanger for small ocean thermal energy power generation devices in the future.

Uncrewed Wave Gliders (UWGs) are capable of harnessing energy from ocean waves and photovoltaic sources to enable long-duration voyages. Since the float’s yaw motion relies on the rudder of the submersible for control, this introduces many unknown nonlinear and time-delay factors into the control system. Moreover, the susceptibility of UWGs to waves influences results in limited maneuverability and necessitates energy efficiency considerations, complicating the task of following a designated path to a specific point for observations. To address these challenges, this paper first introduces a differential model-free adaptive control (DMFAC) approach for managing the float’s heading control, along with a proof of its stability. Furthermore, an improved attractive force line-of-sight (IAFLOS) guidance strategy for overall mooring control is proposed. The integration of the DMFAC heading controller and the IAFLOS strategy forms a comprehensive mooring control system, which is validated through simulation studies in typical maritime conditions. This control system ensures that, while considering energy conservation strategies, the distance between the wave glider and the mooring point remains within 20 m during mooring.

Taking a small long-endurance unmanned surface vehicle (USV) with a trapezoidal cross-section deck structure as the research object, this study investigates the power generation characteristics of a heterogeneous photovoltaic (PV) system consisting of two symmetrically arranged PV arrays with different orientations, under various electrical connection schemes, tilt angles, and heading angles. A PV power prediction model that accounts for dynamic USV attitude changes was established, and the simulation model was validated based on a trapezoidal deck test setup with a tilt angle of 26.6°. Using this model, the daily cumulative energy yields of the independent and parallel configurations were simulated and analyzed under different tilt and heading angles, focusing on the power generation efficiency of the heterogeneous PV system under seakeeping hull constraints. The results show that at a tilt angle of 24°, the daily cumulative energy yield of the heterogeneous system is approximately 95% of that of the horizontal layout, indicating that the trapezoidal frame structure maintains high power generation efficiency while improving wave resistance. The heading angle has only a minor effect on the daily cumulative energy yield, suggesting that variations in course during marine navigation have little impact on power generation. Nevertheless, a significant coupling effect exists between heading angle and tilt angle. Taking a tilt angle of 60° as an example, when the heading increases from 0° to 90°, the energy yield deficit increases from 26.5% to 30.5%. The parallel configuration exhibits slightly lower energy loss at non-south headings and offers a simplified system structure, although its absolute energy yield is marginally lower at large tilt angles. These findings provide practical design guidance for heterogeneous PV systems in sustained ocean observation, climate research, and other long-duration marine missions. Future work will focus on sea trials, hybrid energy integration, and durability studies to further validate and extend these findings.