With the rapid increment of energy consumption worldwide, the caused environmental contamination and global warming desperately necessitate the further development of renewable energy technologies. This study aims at presenting an in-depth investigation of a novel solar-assisted heat recovery heat pump (SAHR-HP) system for heating, cooling and domestic hot water (DHW) supply to resolve some barriers of the existing solar-assisted heat pump (SAHP) technologies, which include (1) performance reduction on the rear collectors of a solar collectors array; (2) poor performance at low ambient temperature; (3) long responding time due to the huge volume of the heat storage and exchange unit (HSEU); and (4) weak of strong complementarity between solar collector and heat pump. According to the barriers, the novel SAHR-HP system incorporates (1) a new designed mini-channel solar thermal collector with three inlets and outlets that can be connected with other solar collectors flexibly; (2) a solar collectors array with a novel multiple-throughout-flow connection method that can simultaneously increase the overall solar thermal efficiency and reduce the flowing resistance; (2) a novel vapour injection heat recovery air source heat pump (VIHRASHP) that can use both the exhausted air and the ambient air, thus leading a considerable performance increase of the heat pump in cold weather; (3) a novel fastresponding double-layered HSEU that can significantly shorten the response time.The study combined theoretical analysis and experimental and simulative investigation, including the following elements; a critical literature review, optimal preliminary design, theoretical analysis, the development of simulation models, prototype construction, laboratory-controlled and field testing, validation and performance optimisation of the simulation models, energy performance, economic performance and environmental influence analysis. The proposed SAHR-HP system has a COP from 3 to 8 according to the weather conditions. The multiple-throughout-flowing connection can improve solar thermal efficiency of a solar collectors array by 10% when compared with that of the conventional one-to-one connection. The novel HSEU can decrease the responding time to 20mins compared with the 3 hours of the conventional HSEU with the same heat storage volume. Particularly, the VIHR-ASHP can save about 23% of electricity consumption as compared with a conventional ASHP at normal operation conditions of condensation temperature of 45°C and an ambient temperature of -10°C. A lower ambient temperature will increase its advantages over conventional air source heat pump and vapor injection heat pump. The integral test results indicated that the SAHRHP system can perform in perfect union with the coordinative operation between different parts of the system under any environmental conditions. The energy performance and the economic and environmental analysis illustrated that this system could efficiently provide enough energy for space heating, cooling and DHW with high energy performance in cold climatic regions, such as Chongqing, Taiyuan and Urumqi. Compared with the coal-driven system, the novel system has a cost payback period of 13.8 years, 12.37 years, and 17.85 years in Chongqing, Taiyuan, and Urumqi and a life- cycle net cost saving of nearly 16145.84RMB, 20317.82RMB, and 9002RMB. Furthermore, the system reduces the emission of many other harmful substances, i.e., dust, SO2 and NOx, and is therefore a desirable approach for environment sustainability and clean air. Besides, the results can be extended to most cold areas worldwide, i.e., The UK and the European countries.The research results are expected to configure feasible solutions for future SAHP technologies. The wide promotion of these core technologies worldwide could significantly reduce the consumption of fossil fuel and the associated carbon footprint in a built-up environment, thus providing a more ecological environment
