Combining solar thermal collectors and heat pumps into a single solar-assisted heat pump (SAHP) system is a promising technology for offsetting domestic hot water (DHW), space-heating, and cooling loads more efficiently. Task 44 of the Solar Heating and Cooling (SHC) Programme of the International Energy Agency (IEA) is currently investigating ways to optimize solar and heat pump systems for residential use. This paper presents a review of past and current work conducted on SAHP systems. Specifically, the key performance data from many studies are highlighted and different system configurations are compared in order to establish insight toward which system configurations are suitable for the Canadian residential sector. It was found that the most suitable configuration for Canadian residential buildings depends on a combination of factors which include occupant behavior, building characteristics, operation parameters, system components, and climate. A large variety of configurations and parameters exist and this made analyzing a specific system, comparing differing systems and establishing an optimal design difficult. It was found that different authors used different performance criterion and this inconsistency also added to the difficulty of comparing the studies of different systems.

The combination of solar thermal and heat pump systems as a single solar assisted heat pump (SAHP) system can significantly reduce residential energy consumption in Canada. As a part of Team Ontario's efforts to develop a high performance house for the U.S. Department of Energy's Solar Decathlon 2013 Competition, an integrated mechanical system (IMS) consisting of a SAHP was investigated. The system was designed to provide domestic hot water (DHW), space-heating, space-cooling, and dehumidification. The system included a cold and a hot thermal storage tanks and a heat pump to move energy from the low temperature reservoir to the hot reservoir. Solar thermal collectors supplied heat to the cold storage and operated at a higher efficiency due to the heat pump reducing the temperature of the collector working fluid. The combination of the heat pump and solar thermal collectors allows more heat to be harvested at a lower temperature, and then boosted to a suitable temperature for domestic use via the heat pump. The IMS and the building's energy loads were modeled using the TRNSYS simulation software. A parametric study was conducted to optimize the control, sizing, and configuration of the system. The simulation results suggested that the investigated system can achieve a free energy ratio (FER) of about 0.583 for the high performance house designed for the Ottawa climate.