Open Access

REVIEW

A Review of Recent Advances in the Application of Solar-Air Source Heat Pump Systems

Haogen Li¹, Guangbai Ma², Haiying Xu³, Shumei Zheng³, Zhe Geng³, Shuzhen Zhang³, Suoying He^1,*, Ming Gao¹, Muzaffar Ali⁴, Ghulam Qadir Chaudhary⁵
1 School of Nuclear Science, Energy and Power Engineering, Shandong University, Jinan, China
2 School of Intelligent Manufacturing and Control Engineering, Qilu Institute of Technology, Jinan, China
3 Shandong Hetong Information Technology Co., Ltd., Jinan, China
4 Energy Engineering Department, University of Engineering and Technology, Taxila, Pakistan
5 Mechanical Engineering Department, Mirpur University of Science and Technology, Mirpur, Pakistan
* Corresponding Author: Suoying He. Email:

Energy Engineering https://doi.org/10.32604/ee.2026.086013

Received 22 May 2026; Accepted 02 July 2026; Published online 04 August 2026

Abstract

Solar-air source heat pump (SAHP) systems integrate solar thermal or photovoltaic resources with air-source heat pumps (ASHPs) to support low-carbon building heating. This integration can reduce solar intermittency and mitigate ASHP performance degradation in cold climates by raising the evaporating temperature, improving renewable-energy self-consumption, and stabilizing heat supply. However, current SAHP deployment is still constrained by rigid control logic, frosting and compressor stress under extreme cold conditions, high initial investment, and inconsistent performance evaluation across studies. To address these issues, this review systematically summarizes recent advances in SAHP architectures, including direct-expansion SAHP (DX-SAHP), indirect-expansion SAHP (IDX-SAHP), photovoltaic-coupled SAHP (PV-SAHP), photovoltaic/thermal-coupled SAHP (PV/T-SAHP), and building-integrated photovoltaic/thermal SAHP (BIPV/T-SAHP). A standardized comparison framework is introduced using COP, SPF, solar fraction, energy-saving rate, exergy efficiency, economic indicators, carbon-emission reduction, system complexity, and climate adaptability. The review further discusses supporting technologies such as thermal storage, active thermal management, vapor injection, model predictive control, reinforcement learning, BEMS integration, and photovoltaic-energy storage-direct current-flexibility (PEDF) systems. The findings indicate that SAHP systems can become core energy units for green buildings only when thermodynamic optimization, intelligent control, cost reduction, and architectural integration are developed together.

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Keywords

Solar thermal; solar photovoltaic; air source heat pump; heating system; building decarbonization

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