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Investigation of a Hybrid Photovoltaic Thermal Heat Pump System

The decrease of photovoltaic (PV) cell temperature by 10 °C is expected to improve the PV electrical efficiency by 0.6-0.7% based on the reference efficiency of 15%. Different cooling liquids like air and water have been introduced to pass across the PVs to reduce the cell temperature, and thus increase the electrical efficiency. In this paper, the refrigerant R134a was used as the cooling liquid and a PV/thermal (PV/T) collector was coupled with a heat pump system acting as the evaporator, which was expected to achieve a better cooling effect and energy performance due to its low boiling temperature. A hybrid PV/T collector, made of 6 glass vacuum tube – PV module – aluminum sheet – cooper tube sandwiches connected in series, worked as the evaporator of the heat pump system. Numerical steady models were established for each component of the heat pump system and part of the PV/T collector/evaporator for predicting their energy performance under the weather data of January 14th at Tibet, China. The results showed that the maximum COP could reach up to 7.6. The daily average thermal efficiency and electrical efficiency were 0.764 and 0.104, respectively.