Analysis of a coupled air-based solar collector and heat pump water heater in Canada and the United States

Heat pump water heaters (HPWHs) have limited market share in Canada and the United States largely due to their space cooling effect which increases heating costs throughout winters in these countries. Coupling a HPWH with solar collectors lessens the space cooling effect during cold-climate heating seasons while also improving HPWH performance year-round in cold and moderate climates. This study experimentally and numerically examined air-based solar collectors and their impact on HPWHs with the objective of determining the feasibility of solar assisted HPWHs in Canada and the United States. An air-based solar collector was used in an experimentally validated model of the combined system, and different configurations of solar-assisted HPWH (SAHPWH) were analyzed to minimize the space cooling effect and electricity consumption. The results indicate that the space cooling effect of HPWHs can be mitigated by coupling the HPWH with a solar collector in all configurations studied. The configurations of SAHPWH which minimized water heating electricity consumption for each Canadian and American location studied were determined, and a correlation was found between climate zone and the configuration with minimum electricity consumption. The maximum electricity reductions from an electric water to a SAHPWH were realized near the Canada and US border, and with a 5% transition to SAHPWHs, Canadian residential energy for water heating can be decreased by 3.1%