•Improved thermal models for Floating Photovoltaic systems is proposed.•The performances of used software tools have been verified experimentally.•The optimal geometrical configurations of floating photovoltaics are investigated.•A comparison of monofacial or bifacial Photovoltaic modules in floating systems is considered. The aim of this study is to create usable commercial simulation software tools for photovoltaic (PV) systems even in the case of floating applications. Using the experimental data of a plant installed at the “Enel Innovation Lab” in Catania (IT), adequate heat exchange coefficients of the software's thermal models were found, which allowed us to take into account the thermal effects for these types of installations. An optimization of the sizes for mono- and bifacial floating systems was carried out. The simulated data for a ground system were compared with the floating data through performance indices. In addition, monofacial models were compared with bifacial. The optimized variables are the tilt angle and the pitch, whereas for the bifacial systems, the module elevation is also considered. The albedo is a sensitive factor mainly for the bifacial modules, so it was considered a parameter in the different design solutions. The simulations were performed by two specialized commercial software programs, where different PV system models are implemented. The normalized annual energy yield was chosen as a meaningful parameter with which to compare the different solutions. As the analysis of PV systems is highly site dependent, the study was developed for two locations, characterized by different diffuse and albedo solar irradiance components, specifically at high latitudes (Frankfurt, DE) and at intermediate latitudes (Catania, IT).