This study presents elements of reflection regarding the most basic optimization parameter of any Wave Energy Converter (WEC): what is the right size for a WEC? The question of scale of tank tests and right size for a given WEC concept is a recurrent one, this study challenges to common request to fix at an early stage the WEC “full scale” size, and discuss the broader implications of the WEC size over its commercialization life. To do so, and in addition to the annual production and capture width ratio, metrics related to the CAPEX utilization, and the impact of maintenance periods on the annual production are introduced. Using the case study of the Sloped IPS buoy, values for these metrics are shown as a function of the WEC scale for four typical wave sites of different characteristics. The results show that scaling up WECs will indeed be more challenging than scaling up wind turbines, and that the main factor hampering such evolution is the rate of increase of the CAPEX that is superior to the rate of increase of the WEC production with scale. However, the results show that there is an advantage for larger WECs, based on the evolution of the maintenance availability. Larger WECs will benefit from longer predictive maintenance windows in the low season with lower impact on their annual productivity. Large farms of mature devices with lower need for corrective maintenance could benefit from such characteristics. It could therefore be expected that as WECs mature and larger farms are considered, their optimal size for a given resource will increase. Additionally, the results emphasise the fact that simplistic OPEX models are not sufficient to properly assess
the size of a WEC for a given project.