Residential space heating electrification through a PV-driven hot water heat pump
Zheng Wang, Mark Luther, Peter Horan, Jane Matthews, Chunlu Liu
Abstract
As the world progresses towards decarbonisation, solutions for houses dependent on fossil fuels are required. Solar photovoltaic (PV) and heat pumps are attractive in reducing carbon emissions due to their renewable energy generation and outstanding energy efficiency. Therefore, this paper investigates the energy, economic and environmental performance of electrifying fossil fuel-based space heating systems through PV-driven hot water heat pumps. A case study was conducted on a typical Australian house with a 10 kW PV, a hot water heat pump, and a gas-ducted heater. Transient System Simulation (TRNSYS) was employed to simulate the existing space heating and hot water system (ESH): a gas ducted heater + a PV-driven hot water heat pump and the proposed space heating and hot water system (PSH): a heating tank + a heating element + fan coil units + a PV-driven hot water heat pump. The simulated space heating loads, PV generation and heat pump power consumption, were verified using actual measurements. Results demonstrated that PSH eliminated the annual gas demand of 4093 kWh needed for ESH. Additionally, the annual PV self-consumption and self-sufficiency increased by 26 % and 50 %, respectively, from the previous levels of 19 % and 29 % due to the electrification of the space heating system. After determining the optimal sizing of the heating tank and its immersed heating element based on the high PV energy utilization rule, it was discovered that a payback period of 12.3 years was required for transitioning the house from ESH to PSH with an annual carbon emission reduction of 24 %. This work demonstrated the feasibility of electrifying the conventional fossil fuel-based space heating system to fan coil units and a heating tank connected to a PV-driven hot water heat pump, thus contributing to the decarbonization of future homes.