Over the years, many research efforts have been spent on the development of hybrid photovoltaic thermal (PVT) technology, which is able to produce electricity and thermal energy at the same time with better overall performances of the two separated solar technologies. The aim of this work is the design of an innovative glazed PVT component with water as heat transfer fluid and the construction of a detailed mathematical model for the estimation of its electrical and thermal production. The paper presents the design of a covered PVT collector, made with thin film PV technology and a roll-bond flat plate absorber, and a simulation model, developed through the elaboration of several mathematical equations, to evaluate the performance of covered PVT water collectors. Finally, considerations about daily and annual yield of the proposed PVT collector, compared to a standard photovoltaic module, are discussed. (C) 2014 Elsevier Ltd. All rights reserved.