<![CDATA[Sustainable maritime transportation requires electrical systems that are reliable, energy-efficient, and capable of integrating cleaner energy sources. This study develops and evaluates a small-scale hybrid power prototype that combines a 50 Wp photovoltaic (PV) source as the renewable-energy component with a mini steam power source as a complementary generator, using an ESP32 microcontroller, INA219 sensors, MPPT control, a buck-boost converter, and relay-based automatic switching. The experimental program included static component verification and dynamic tests under changing solar irradiance, steam pressure, source-transfer conditions, smartphone monitoring, and 180-minute battery-charging cycles. The PV source produced 11.1–19.7 V and 0.8–2.6 A depending on weather conditions, while the mini steam source became stable from approximately 20 psi and produced 23.3–24.5 V and 2.2–2.5 A between 20 and 50 psi. Automatic source switching occurred in approximately 0.2 s in all five trials. Both charging paths raised battery voltage to 12.8 V at 90 min, after which charging was automatically disconnected. These results show that renewable-energy utilization can be strengthened by hybrid-source coordination, real-time monitoring, and energy storage to support continuity of power for maritime transportation. From a Vessel-to-Grid (V2G) perspective, the prototype demonstrates enabling functions at the onboard energy-management level, but bidirectional power export to an external grid was not tested and remains a subject for further development. .]]>
