Wave-Motion-Induced Photovoltaic Efficiency Correction for a Hybrid Wind–Solar Power Buoy in Offshore Cage Aquaculture: Modeling and Sensitivity Analysis

Photovoltaic panels on a floating platform are tilted by wave-induced roll and pitch, and a tilted panel collects less light. This loss is usually neglected when hybrid wind–solar systems are sized. This paper estimates the loss for a small wind–solar buoy that powers offshore fish cages in the Yellow Sea. The buoy is modeled in ANSYS AQWA to obtain its roll and pitch response to waves, and the response is converted into a factor that corrects the calculated PV output. The factor depends on the square of the tilt amplitude and on the direct-beam fraction of the sunlight, so it can be evaluated directly once the wave response of the platform is known. Three buoy forms were compared, and a hemispherical buoy of 1.8 m diameter was selected. Its roll and heave natural periods, 2.86 s and 2.50 s, are shorter than the dominant wave period of 4.5–4.8 s, so the roll amplitude in the working sea state is only about 3° and the loss is only 0.1%. This is one to two orders of magnitude smaller than the 4–6% loss caused by the module temperature, so the static model is adequate for this buoy; the same factor gives 2–5% for a platform that rolls 15–25°, which shows when the wave motion has to be included in the energy balance. Wind speed and irradiance dominate the output, and a full-scale prototype confirmed the hydrodynamic and static power models to within 4%.