摘要： The building’s energy demand consists of both thermal energy and electricity that may be provided through solar energy sources. Typically, the electrical energy needs are satisfied by photovoltaic plants (PV)s, while the thermal energy needs are satisfied by solar thermal plants (ST)s. However, there is the possibility to produce simultaneously electrical and thermal energy by hybrid photovoltaic/thermal (PV/T) plants. This study presents the comparison of the performances of a hybrid photovoltaic/thermal (PV/T) plant with those of a systems made by a PV plant plus a ST plant (PV+ST). Such comparisons are interesting in those buildings where there is not enough available surface for installing both PV and ST plants as much as necessary for satisfying the energy needs of such buildings ( e.g. in residential tower buildings). This research is carried out having as target a residential unit situated in different geographic areas: Catania (IT) , Split (HR) and Freiburg (D). The outcomes of the energy analysis, calculated following the first and the second thermodynamic law approach, highlight that a PV/T plant produces more energy than a conventional solar system (PV-ST) in the three cities. Otherwise, the results of the economic analysis show that the PV plants allow to achieve the most economic benefits due to the cheaper cost of this technology.