Simulation study of a ground-source heat pump (GSHP) system coupled with photovoltaic thermal collectors (PVT) in cooling-dominated buildings

A novel ground-source heat pump (GSHP) system with an array of solar photovoltaic-thermal (PVT) modules for cooling-dominated buildings is proposed in this study. The purpose of the PVT array is to remove annual ground thermal load imbalances on the ground-loop heat exchanger (GLHE) to assist in achieving an optimally-sized GLHE. The PVT array operates by generating electricity during the day via the photovoltaic effect, and unloading thermal energy from the ground during the night via combined convection plus sky thermal radiation by means of pipes bonded to the back of the PVT panels. To examine the merits of the proposed concept, U.S. Department of Energy reference building loads for a school building in Phoenix, Arizona were used to construct a computer model of a GSHP + PVT system in the TRNSYS modeling environment. System simulations were conducted for a 20-year life cycle for designs with and without the PVT subsystem to determine the potential size reduction of the GLHE with the PVT array. The results of this study showed that by including a PVT array of 4962 m2 for the modeled school building, a 56% reduction in size of the GHLE is possible. In addition, the hybrid system reduced the implementation cost and supplied 26% of the electricity load of the building.