The overall system optimisation of wave energy converters remains a challenging task. Firstly, this is associated with the large number of system parameters and their related constraints, secondly, the complexity of numerical system representations capturing overall system behaviour and, thirdly, the uncertainties in the prediction and formulation of appropriate overall economic system performance objectives. The parameterisation and the modelling challenges require a staged approach for an overall system optimisation. This ranges from simplified system representations exposed to variations within a large parameter space to more sophisticated system models subject to evaluation for a reduced and focused parameter zone. The description of the system dynamics, operation and performance needs to capture the key characteristics of the WEC concept functionality, the technical implementation and the economic application from the beginning and throughout the optimisation and development process. The paper describes the problems that are associated with the widely employed sequential development of wave energy converter (WEC) systems from concept through technology to economic application and presents the methodology applied to the overall techno-economic system optimisation and development process of Wavebob WECs.