Numerical Modelling of Current-Induced Loads on Offshore Floating Photovoltaics Systems

Abstract

Offshore floating photovoltaics (OFPV) have emerged as a scalable alternative to land-based PV by utilizing vast ocean space near densely populated coastal areas. In addition to wind and wave loads, these systems are exposed to tidal currents, where the resulting current-induced loads scale with the floater’s reference area. As OFPV systems scale in size, accurately predicting these loads becomes increasingly crucial for safe and efficient design. This study investigates the influence of the floater’s shape, specifically its draft and leading-edge bow angle, on current-induced loads.

To this end, a two-dimensional Computational Fluid Dynamics (CFD) model is developed using OpenFOAM to simulate the flow around a single OFPV floater under current-only conditions. The model applies a URANS (Unsteady Reynolds-Averaged Navier-Stokes) approach with the k − ω SST (Shear Stress Transport) model. Hydrodynamic performance is evaluated through pressure drag, viscous drag, lift and pitching moment coefficients.
Results indicate that decreasing the draft, thereby streamlining the overall shape, reduces the downward lift and pitching moment coefficients, while pressure drag remains constant and viscous drag increases. In contrast, streamlining the leading edge of the floater reduces pressure drag, downward lift and pitching moment coefficients, at the cost of a higher viscous drag.
Overall, these findings suggest that streamlining the edges of the floater is the most effective strategy to improve hydrodynamic performance of OFPV floaters.
While the model successfully captures these trends, it is subject to several limitations that present opportunities for future refinements. These include the absence of experimental validation data, simplified environmental conditions, and constraints of the numerical modelling approach.