Techno-economic and environmental study of a hybrid solar ground source heat pumps for a heating-dominated community in a cold climate; a case study in Toronto

Employing ground source heat pumps (GSHP) in heating-dominated areas presents challenges, including load imbalance and decreased efficiency. This study examines using solar energy to prevent soil thermal depletion in cold climates by comparing two systems. The first system (HPPV) uses geothermal heat pumps, borehole thermal energy storage, and photovoltaic modules. The second system (ST-HPPV) adds solar thermal collectors to reduce soil thermal depletion over long-term operation. Both systems supply hot or chilled water to the community's fan-coil systems via a short-term storage tank and heat exchanger. Their energy performance, greenhouse gas emissions, and costs were compared with a conventional fossil-fueled system (natural gas boiler and absorption chiller). Results showed the ST-HPPV system outperformed the HPPV system by 15 % in the seasonal coefficient of performance in heating mode after 20 years. However, solar thermal collectors did not benefit the cooling mode due to the community's load characteristics. Cost analysis revealed the HPPV system is more cost effective and reliable due to lower operating and carbon costs. The findings recommend the ST-HPPV system for communities where the annual heating load is 75 % or more of the cooling load.