This article reports on the evaluation of the short and long-term electrical performance of a photovoltaic-thermal (PVT) system coupled with borehole thermal energy storage (BTES). This assessment was conducted using a computer simulation of a PVT system installed on a small office building in two extreme climate zones in the United States. In each climate, two different scenarios were considered: (i) a PVT system coupled to a BTES with no ground-coupled heat pump (GCHP), and (ii) a PVT system coupled to a BTES with a GCHP. The system simulation results reveal significant improvements in PVT cell efficiency in the system without a GCHP compared with conventional PV panels. These improvements were reported to be as high as 4.1 and 4.7% in cold and hot climates, respectively. Moreover, a coupling GCHP showed a negligible impact on the PVT cell performance, which implies the feasibility of coupling the two technologies to the same BTES.