The roadmap to a successful commercialisation of wave energy inherently incorporates the concept of an array or farm of Wave Energy Converters (WECs). These interacting hydrodynamic structures require an optimised process that can ensure the maximum extraction of time-averaged energy from ocean waves, while respecting the physical limitations of each device and actuator characteristics. Recently, a novel optimal control framework based on the concept of moment, for a single WEC device, has been introduced in [1]. Such a strategy offers an energy-maximising computationally efficient solution that can systematically incorporate state and input constraints. This paper presents the mathematical extension of the optimal control framework of [1] to the case where an array of WECs is considered, providing an efficient solution that exploits the hydrodynamic interaction between devices to maximise the total absorbed energy.