System design and robust planning of a solar vapor generation based islanded water-energy nexus polygeneration system

To address energy demands on isolated islands, this study proposes a marine off-grid water-energy polygeneration system. By utilizing phase change materials and solar vapor generation devices, the system achieves integrated water-heat coupling, and establishes a thermo-electric exergy equivalence model. A scenario robust multi-objective optimization framework that considers both normal and multi-level typhoons is proposed for extreme weather on islands, which comprehensively evaluates cost, reliability, and robustness to achieve optimal system capacity configuration. Results show that optimal sizing expands energy storage capacity while reducing the rated power of instantaneous heat conversion units. With the annual investment cost standing at the median of the configuration range, the daily operational reliability and extreme scenario robustness reach 88.6 % and 95.9 % respectively. The system maintains a 100 % supply reliability for both freshwater and electricity across various severity levels of typhoon scenarios. Sensitivity analysis further reveals that the interfacial solar vapor generation device is the core of daily system operation. Phase change materials not only function as thermal energy storage media but also serve as the key coupling hub between the water and heat subsystems. This research provides a practical and reliable energy security scheme for standalone marine bases.