Critical review of solar-assisted air source heat pump in China

In northern China, promoting low-carbon heating technologies is pivotal in improving air quality and reducing carbon emissions. Solar-assisted air source heat pump systems have attracted extensive attention for the advantages of high energy efficiency and low carbon emissions. However, the existing reviews on solar-assisted air source heat pump systems mostly focus on technique development. This study comprehensively investigates the challenges and opportunities faced by solar-assisted air source heat pump systems in the combined aspects of technology, economy, and policy in China. Technical obstacles under diverse climate conditions, inefficient thermal energy storage, long payback periods, and a lack of subsidy policies pose significant challenges to solar-assisted air source heat pump systems. The main concerns of the solar-assisted air source heat pump system for the user, government, and manufacturer are costs, the financial burden of subsidy, and investment risk, respectively. Advances in new technologies, energy storage materials, defrosting, and optimization methods are promising to improve the performance of solar-assisted air source heat pump systems. Favourable renewable energy policies, energy performance contracting mode, and integrated energy systems give solar-assisted air source heat pump systems a bright future in China. Based on these identified factors, a SWOT (strengths, weaknesses, opportunities, and threats) analysis is conducted to propose strategies for the advancement of solar-assisted air source heat pump systems. This work is expected to give valuable insights to researchers, users, manufacturers, and policy makers for the promotion of solar-assisted air source heat pump systems towards low-carbon space heating.