Floating photovoltaic power plants represent one contemporary new alternative to terrestrial PV systems. In this study, which was based on an examination of three different floating photovoltaic systems that were installed on Buyukcekmece Lake in Istanbul with an output of 9 kWp, 90 kWp and 30 kWp, we carried out an assessment of the difficulties and critical faults that can arise with such systems. During the course of the study, it was found that warpage of floating photovoltaic elements as a consequence of harsh wave action is one of the most serious problems that may be encountered. Tests of structural fixity, one-way motion and semi-flexible fitting elements revealed that they are not suitable for floating photovoltaic systems. A comparison of previously installed systems with our new 30 kWp floating photovoltaic designs indicated that the latter were robust and sustainable even with the severe wind and wave conditions on Buyukcekmece Lake for the period of research, which ran between July 2018 and April 2020. Our research also indicated that most of the well-known float and frequently used designs for floating photovoltaic systems are not sufficiently robust for severe environmental conditions. This study provides two significant yet contrary outcomes for floating photovoltaic designs, namely that systems as a whole must be flexible while individual units need to remain stable.