For energy generation devices such as wave energy converters (WECs), techno-economic performance should be considered early in the development process, when fundamental conceptual, operational and design choices are being made. Hence, the Technology Performance Levels (TPL) were designed to consider a wide range of WEC attributes that define the technoeconomic performance potential as well as identify potential showstoppers at the earliest stages of WEC development. The original groups and attributes of the TPL assessment used in the Wave Energy Prize have been updated using a formal Systems Engineering approach. This paper will detail the process of determining the assessment questions for each capability (a condensed list of stakeholders’ requirements) in the TPL taxonomy. These questions direct the assessor towards the most appropriate considerations for a given capability. The scoring criteria give guidance on how to rank the answer to the assessment questions. The assessment questions combined with the scoring criteria allow for the technology to be numerically ranked on the TPL scale. Details on the calculations required to obtain a TPL score for a device are presented.