The feasibility of coupling a ground source heat pump (GSHP) with photovoltaic-thermal (PVT) energy sources was demonstrated by researchers from KTH Royal Institute of Technology, Sweden.

An experimental heating system was designed with roll-bonded PVT collectors featuring embedded channels between two rolled aluminum sheets, which have a higher heat transfer coefficient compared to conventional PVT panels using sheet and tube absorbers. Five PVT collector designs were evaluated at fluid temperatures below ambient in combination with a GSHP under wide range of low-temperature operating and weather conditions through outdoor laboratory experiments in Stockholm. In the proposed system configuration, the PVT collectors act as secondary heat sources.

Box-channel aluminum PVT collectors with fins produced more heat per square meter compared to their conventional counterparts. Despite having a relative specific thermal cost 9% higher than the reference collector, this design demonstrates the capability to generate 2,096 kWh/m2 per year of thermal energy, marking an 83.3% increase compared to the reference, with a 136% higher energy-to-mass ratio.

The box-channel aluminum collector described in Applied Thermal Engineering is recommended for integration with ground source heat pump systems. An aluminum finned tube design proved similar in performance but has a significant cost disadvantage. Of the non-finned designs, the sheet and tube collector offers a similar thermal unit cost as the finned box channel aluminum design but delivers 40% less heat per square meter annually.

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