Thermal and economic assessment of ground-coupled storage for residential solar heat pump systems

This study performed an analysis of ground-coupled stand-alone and series configured solar-assisted liquid-to-air heat pump systems for residences. The year-round thermal performance of these systems for space heating, space cooling, and water heating were determined by simulation and compared against non-ground-coupled solar heat pump systems as well as conventional heating and cooling system in three geographic locations: Washington, D.C., Fort Worth, Texas, and Madison, Wisconsin. The results indicate that a combined solar/ground-coupled heat pump system for space heating and cooling is not cost-effective. However, a ground-coupled stand-alone heat pump system using either a conventional domestic hot water system or a separate solar water heating system has significant energy savings as compared to conventional furnace systems. It also has some energy savings over conventional air-to-air heat pump systems, particularly in Washington, D.C. The cost of that saving is not beyond that which the average consumer can be expected to pay. Therefore, the ground-coupled stand-alone heat pump system is a cost-competitive system.