This paper presents the simulation and performance evaluation of a ground source heat pump (GSHP) system integrated with water-based solar photovoltaic thermal (PVT) collectors for residential buildings. A dynamic simulation system is developed using TRNSYS and used to facilitate the performance evaluation of the system. A 20-year life-time performance simulation is performed under three operation scenarios with different sizes of the PVT collectors. The results showed that the performance of the system is highly dependent on the size of the PVT collectors. Furthermore, an economic analysis is carried out to determine the optimum size of the PVT collectors for the case study building.