Sizing a Stand-Alone Wind–Photovoltaic DC Microgrid for Offshore Aquaculture: Delivered Energy, Load Coverage and Storage Requirements

Whether a stand-alone wind–photovoltaic supply is adequate depends more on how its load is described than on how it is rated. Sizing starts from component ratings and a peak load, yet the annual energy balance that follows says nothing about whether the load is served in every hour, and one installation can look comfortable under one description of its duty and insufficient under another. We size such a supply for an offshore cage farm in the northwestern Yellow Sea and test it against ten years of hourly reanalysis data. The annual margin over a monitoring and control load is wide, while the same hardware meets only a small part of a demand that draws full power continuously. The hourly simulation qualifies the first verdict: part of the critical demand is unserved, the longest lull outlasts the battery, and added storage closes the gap slowly. The site’s two resources are out of phase but only weakly complementary, so generation and storage must be sized for the wind season alone. The resource carries the uncertainty. Annual adequacy establishes a margin rather than continuity, and the storage is set by the load-duration curve.