Floating photovoltaic (FPV) systems offer notable benefits over traditional land-based ones. These include the abundant surface area available for arranging panels in large arrays, the opportunity to leverage the cooling effect of sea water on panel efficiency, as well as the possibility of integrating solar tracking technologies in a cost-effective manner. However, their application in offshore and coastal environments has been challenging due to the interaction between FPV structures and waves, as well as other environmental conditions. In this study, a twin-hull floating platform is examined, which features improved stability characteristics, combined with a lightweight structure and high mobility. A boundary element method (BEM), developed for simulating the hydrodynamic behaviour of floating systems, is employed to calculate wave-induced responses and their impact on the system's power generation. The influence of wave-induced dynamic motions on FPV performance is analyzed, showing significant fluctuations of power output depending on the sea state. Preliminary data regarding the performance of a specific module in a selected coastal region of the Greek Seas is presented and discussed, demonstrating the applicability of the proposed methodology.