Seakeeping analysis of catamaran and barge floats for floating solar arrays: A CFD study with experimental validation

Whilst floating photovoltaic (FPV) is gaining attention for ocean-based applications, their motion response in waves significantly affects structural integrity and power generation efficiency. In particular, FPV is expected to operate in arrays consisting of extensive solar panels, and thus, floating solar systems are required to be analysed with neighbouring devices connected by joints. This study investigates the seakeeping characteristics of two FPV systems in arrays, comparing conventional barge floats with twin-hull (catamaran) floats under various wave conditions. A systematic investigation using Computational Fluid Dynamics (CFD) was conducted for the hydrodynamic response of both isoslated-single-floater and multi-body (1 x 3) configurations in regular waves, with non-dimentional wavelength ratio (lambda/L) 1.62-4.27 to the floater length. Wave tank experiments were conducted to validate the CFD model, showing agreement with less than 10% discrepancies. The study focused on the multi-body behavior of heave and pitch Response Amplitude Operators (RAOs) and mooring line forces. Results show that the multi-catamaran configuration exhibited lower heave RAOs (by approximately 20 degrees%) compared to multi-barge pontoons in long waves (lambda/L > 2.47) while maintaining similar pitch responses. However, in shorter waves (lambda/L < 2), the catamaran configuration showed up to 15% higher RAOs than barge's. The multi-body arrangement demonstrated significant array effects, with the leading float experiencing 30% higher mooring loads than the trailing float. The leading float also experiences the highest mooring forces. As the wavelength ratio increases, the barge float's front mooring force increases dramatically, reaching nearly twice that of the catamaran at a ratio of 4.27. These findings align with the RAO results, indicating that the barge float is more wave-sensitive under long-wavelength conditions, whereas the catamaran demonstrates superior station-keeping with lower mooring forces. This work provides quantitative guidance for selecting appropriate floater forms for FPV applications based on expected wave conditions.