Hybrid photovoltaic/thermal and ground source heat pump: Review and perspective

• Published in: Renewable & sustainable energy reviews 2021-11, Vol.151, p.111569, Article 111569
• Main Authors: You, Tian, Wu, Wei, Yang, Hongxing, Liu, Jiankun, Li, Xianting
• Format: Article
• Language: English
• Subjects: Energy storage; Ground source heat pump; Hybrid heat pump; Photovoltaic thermal; Renewable energy; Thermal imbalance
• ISSN: 1364-0321; 1879-0690
• DOI: 10.1016/j.rser.2021.111569

Ground source heat pump (GSHP) is widely studied for building energy efficiency but suffers from soil thermal imbalance and performance deterioration in heating-dominant regions. Photovoltaic (PV) collector is commonly used for renewable energy, but the efficiency is constrained by the PV module temperature. The combination of GSHP and photovoltaic/thermal (PVT) is promising to improve the performance of both individual technologies. A comprehensive review has been conducted to present the state-of-the-art of the hybrid PVT-GSHP, in terms of the principles, configurations, and functions. The basic PVT-GSHP systems are classified into four categories: the hybrid PVT-GSHP with PVT for direct heating, the hybrid PVT-GSHP with PVT for temperature increasing, the hybrid PVT-GSHP with multiple energy sources, and the hybrid-GSHP with energy storage/borehole recharge. These hybrid systems can be further combined to achieve advanced hybrid PVT-GSHP systems with more functions and improved performance. For the hybrid PVT-GSHP with PVT for direct heating, preheating and full heating have been used; the preheating yields a higher PV efficiency while the full heating recovers more heat. The hybrid PVT-GSHP with PVT for temperature increasing is more widely adopted, with both PVT electrical efficiency and GSHP heating efficiency significantly improved. For the hybrid PVT-GSHP with multiple energy sources, the current systems were limited to the integration of an air source heat pump as an additional heat source or a cooling tower as an additional heat sink. The hybrid PVT-GSHP with energy storage/ground recharge received the most intensive investigations owing to the reduced thermal imbalance and thus enhanced long-term performance. While most studies used normal flat-plate PVT, advanced collectors including concentrating PVT, building-integrated PVT, and solar-road PVT have also been studied. To facilitate performance improvement and application promotion, some perspectives on future development are presented: (1) advanced ground heat exchangers, i.e., energy geo-structures including the energy pile, energy wall, and energy tunnel; (2) advanced PVT types, i.e., more involvements in the high-temperature PVT and building-integrated PVT; (3) advanced hybrid systems, including driving sorption chillers, regenerating desiccant dehumidifiers, charging thermal batteries; and (4) optimal design and operation, considering local soil properties (e.g. seepage) and climate condit