Economic analysis of heat pump water heaters coupled with air-based solar thermal collectors in Canada and the United States

Abstract

Heat pump water heaters (HPWHs) could reduce residential energy consumption but there are two barriers preventing their uptake: the space cooling effect which increases space heating costs in cold climates and the high capital costs. These barriers may be mitigated by coupling a HPWH with an air-based solar collector to preheat inlet HPWH air, and using a lifecycle thinking approach to evaluate HPWHs or solar-assisted HPWHs (SAHPWHs) to encompass low operating costs. The objective of this study was to economically analyze the HPWH and SAHPWH across Canada and the United States to determine locations in which the systems are economically feasible as a method for reducing residential greenhouse gas emissions. The methodology for this included simulating the HPWH and SAHPWH performance using an experimentally validated TRNSYS model. The results show that HPWHs are typically more feasible than SAHPWHs except in locations with high electricity rates or long heating seasons, or locations with fossil fuel dominant electricity grids when carbon pricing is considered. As such, each location must be studied to determine which options are economically suitable. The findings presented illustrate economical clean water heating options, and subsidies that could be introduced to further encourage uptake of low carbon water heating.