Analysis of solar PV connected heat pump system with integrated thermal energy storage for single-family house.

One of the major goals of European Union is to achieve ambition of reduction in net carbon emissions. Building heating systems are main source for such carbon emissions. For residential heat generation, heat pump has evolved as an energy efficient alternative. The demand of heating can be achieved by renewable energy sources by using PV-connected heat pump system. Total heat demand evaluation is the foremost step to identify the need of the house heating. The maximum hourly demand reached 4.027 kWh, while annual heat demand of house in our case is 8.82 MWh. The fluctuations in external temperature were observed to affect the PV-connected heat pump system in fulfilling heat demand. External temperature influenced COP, heat delivered by heat pump, electricity needed by heat pump, and state of charge of thermal energy storage tank. These season dependent variations show low heat demand covered by PV connected heat pump system in winters, while high heat energy was stored in thermal energy storage tank in summers. These variations are balanced by considering thermal energy storage system cases. In the storage case of the smallest tank size (12 kWh), the use of the grid is maximum. While, for the storage case of medium-sized storage (25 kWh), the grid is used in moderate level. The case with the highest storage size (40 kWh) shows little difference compared to medium sized storage for fulfillment of heat demand. While if seen from an economic perspective, its investment cost is reasonable when compared with the annual savings provided by it, while giving moderate payback time. Hence, medium sized storage is considered feasible according to economic and system perspectives. These cases observed in our work showed that the proper storage size is required when considering renewable energy-based heat generation system. In the results it was observed that increasing the size of thermal energy storagehelps move more towards renewable energy source by covering maximum heating hours using PV connected heat pump system. This supports the environment by reducing effect of carbon dioxide emissions.