This paper investigates the motion characteristics and expandability of modularised floating solar farms in waves, using computational fluid dynamics (CFD) simulations. The study focuses on the wave length to module length ratio (R = L_m/λ) as a key parameter to predict the motions of large floating solar systems in head waves. The results indicate significant impacts on vertical motions, which are predictable based on the R value. The empirical relationship between R and the motion of each unit in an array is established. The study compares the results obtained using the multiple-rigid-bodies method with those from the single-large-hydroelastic-body method, finding similar outcomes when R ≈ 1. This allows for predicting the motion of the entire array in waves through a simplified hydroelastic approach. The insights gained from this research are valuable for the design and optimization of modularised solar farms, addressing cyclic load and motion concerns for long-term durability. The study also highlights the importance of considering wave diffraction and blocking effects in multi-array systems, which are crucial for accurate predictions. The findings provide a foundation for further research on structural resonance, extreme loading, and wave energy dissipation in floating solar farms.This paper investigates the motion characteristics and expandability of modularised floating solar farms in waves, using computational fluid dynamics (CFD) simulations. The study focuses on the wave length to module length ratio (R = L_m/λ) as a key parameter to predict the motions of large floating solar systems in head waves. The results indicate significant impacts on vertical motions, which are predictable based on the R value. The empirical relationship between R and the motion of each unit in an array is established. The study compares the results obtained using the multiple-rigid-bodies method with those from the single-large-hydroelastic-body method, finding similar outcomes when R ≈ 1. This allows for predicting the motion of the entire array in waves through a simplified hydroelastic approach. The insights gained from this research are valuable for the design and optimization of modularised solar farms, addressing cyclic load and motion concerns for long-term durability. The study also highlights the importance of considering wave diffraction and blocking effects in multi-array systems, which are crucial for accurate predictions. The findings provide a foundation for further research on structural resonance, extreme loading, and wave energy dissipation in floating solar farms.