Wave energy is one among several resources of renewable energy which needs to be utilized in the future to solve human’s energy demand. Several technologies have been proposed but yet there are few commercial concepts that have been connected to the grid. The floating wave energy converters (WECs) will have an important role in the supply of electricity in the future. But there are several challenges in their designs on systems and component levels that need to be overcome and solved. There are also challenges related to installation and maintenance. The current paper presents and discusses examples of challenges on component and systems level, with reference to floating WECs. One specific concept is studied in detail with an emphasis on mooring design, fatigue life of elastic mooring systems and umbilical cables, power performance of individual WECs vs WECs installed in wave parks. The levelized cost of electricity method is used to compare some configurations that have been studied in more detail. Examples of results from numerical simulations and full-scale measurements on a floating heave point-absorber are presented.