Performance analysis of a building heating system using ground-source heat pump and photovoltaic thermal collector

In the present research, the performance evaluation of a building heating system equipped to underground storage tank heat pump and photovoltaic thermal collector is carried out. The system consists of an underground spherical tank, a photovoltaic thermal collector and a heat pump. The performance evaluation of the combined system is carried out from the energy and exergy perspective. Developing energy balance for various components of the system, the analytical relations for water temperature of auxiliary tank, solar cell temperature, absorber plate temperature and the useful heat gain of photovoltaic thermal collector are obtained. Output electrical power of photovoltaic module is calculated by the four-parameter current-voltage model. By writing the exergy balance for the various components of the system, their irreversibility is specified. There is a good agreement between the simulation results of the present study and the experimental data of the previous literature. The obtained results indicate that the energy and exergy efficiency is maximum for the collector number of 65 and mass flow rate of 0.25 kg/s. The decrease of storage tank volume causes the decrease of water temperature. The increase of 30% in the collector number causes the increase of 25% in water temperature. The highest and lowest water temperature of the tank is observed on the ground of coarse graveled and granite, respectively.