Integrating PV power and a climate-adaptive heat pump system for sustainable agriculture in solar greenhouses

Promoting energy-saving and emission-reduction measures in China's agricultural sector is crucial for achieving carbon neutrality and ensuring sustainable agri-food development. As the largest arid inland region in the country, Xinjiang holds significant socio-economic importance in national agricultural production. However, research on the potential of on-site photovoltaic (PV) systems in local agricultural greenhouses and their contribution to energy conservation and carbon reduction remains limited. To address this gap, this study evaluates the application potential of on-site PV systems in greenhouses in southwestern Xinjiang, with a focus on their energy and economic performance. Simulation results show that integrating on-site PV generation significantly improves the system's overall performance, reducing annual grid electricity consumption by 20.2%—alleviating future demands for transformer capacity expansion—and achieving a net present value of CNY 0.21 million compared to conventional non-PV systems. Furthermore, this study experimentally investigates a climate-adaptive air-source heat pump coupled with a ground heat exchanger (ASH-GHX) heating system tailored for this region. A key design feature involves placing the evaporator inside the greenhouse to leverage the arid continental climate, where winter sunlight often raises indoor temperatures above 25°C for 4–5 hours daily. This excess heat is captured and stored underground via the ground heat exchanger for nighttime use. The system achieves a daily heating coefficient of performance of 3.4–3.7, with a carbon emission reduction rate of 70.6–72.7% compared to conventional electric heating, and 20.4–21.3% compared to an ASH-GHX system with an outdoor evaporator. It is anticipated the findings can provide valuable insights for advancing low-carbon and sustainable agricultural development in southwestern Xinjiang and other regions facing similar environmental challenges.