Multigenerational performance analysis of a direct expansion PVT-HP system using year-long experimental data

In this paper, a trifunctional direct expansion photovoltaic-thermal heat pump (PVT-HP) system was constructed to provide domestic hot water, photovoltaic power, and chilled water for an activity center of sports in Dalian, China. The thermoelectric evaluation indicators were proposed to unify the single thermal and electrical performances of the system. Then, year-round experiments were conducted to investigate the trigeneration performance of the system in typical seasons. The operation characteristics of the system were analyzed under typical weather conditions in detail. Afterward, the thermal and comprehensive performances of the PVT evaporator were analyzed. The performance curves of the PVT evaporator were determined. Finally, the results demonstrate that the average coefficient of heating performance of the system was 2.92 in winter, 3.69 in summer, and 3.46 in transition season. The average thermoelectric comprehensive efficiency of the system was 33.72 % throughout the year. The average coefficient of cooling performance of the system was 2.62 during nighttime operation in summer. Moreover, the average thermal efficiency and total thermoelectric efficiency of the PVT evaporator were 60.37 % and 70.12 %, respectively. This study can provide a practical reference for the application and evaluation of solar PVT heat pump systems in building retrofit projects.