Novel Modular Design for Floating Offshore Photovoltaic Platforms

Researchers from China and the United States have proposed a novel modular floating photovoltaic (FPV) solution to evaluate the behavior of multiple interconnected modules at sea under combined wind and wave conditions. The team, which included scientists from the Dalian University of Technology and the University of Maine, analyzed different types of fixed and articulated FPV systems to determine possible optimization methods.

"FPVs," the study states, "are complex multibody systems subjected to coupled wind, wave, flow, and other multiphysics fields. Therefore, the development of robust engineering methods and models for the design of FPV systems for offshore environments is of paramount importance.

The analysis found that the kinematic response became more pronounced as the number of modules increased, with the tilt response of the 2 x 2 platform being the strongest for the configurations studied. The team also found that the additional motion generated by the hinge connection resulted in a "non-negligible" dynamic response of the multibody FPV system, while the system with a fixed connection did not exhibit a significant dynamic response. In addition, the researchers found that the anchoring stress was greater in systems with hinged connections than in systems with fixed connections.

In this study, the team presented a novel modular design for the FPV platform that incorporates the concept of a semi-submersible offshore engineering platform. It uses a tubular mooring system based on curves commonly used for moorings of bridges, ships, and offshore platforms. The overall hydrodynamic performance and behavioral characteristics of different types of FPV platforms were evaluated using frequency domain analysis at an offshore site in China's Shandong Province.

The researchers built the FPV platform from a cylindrical pontoon and a wave plate. They installed solar panels on steel beams above the pontoons at an inclination of 10 degrees, with each beam providing at least 250 kilowatts of power per platform. They investigated the movement behavior of the anchored single, 2 x 2, and 3 x 3 FPV systems under extreme conditions.

"The stability of the FPV platforms," say the researchers, "is of crucial importance when it comes to preventing the loss of electrical supply equipment due to capsizing and minimizing damage to the transmission cables." The design of the mooring is therefore crucial to mitigate the dynamic behavior of FPV systems.

The study emphasizes that wave behavior is influenced by the ratio of mass to stiffness. The researchers found that a 2 x 2 FPV system responds most strongly to the wave when the trough is exactly where the two modules meet and the modules have a V-shape. However, the addition of a third row of modules helped to reduce the relative motion so that the "maximum pitching motion of the 3 x 3 platform" was less than the maximum pitching motion of the 2 x 2 platform.

Based on their analysis, the team recommends that multi-body FPV systems should be mounted at an angle of at least 15 degrees to reduce movement and structural response.

The team's findings are published in the research report "Assessment of the dynamic behavior of multi-connected offshore floating photovoltaic systems under combined wave-wind loading: A comprehensive numerical analysis", which appeared in Sustainable Horizons.

"The mooring system can be optimized to further improve performance and reduce platform motion behavior. Such optimization can lead to cost savings and make the overall system more economically viable," the team concludes.