Performance of the hotovoltaic solar-assisted heat pump system with and without glass cover in winter: a comparative analysis

An application of photovoltaic /thermal (PV/T) technology in heat pump, known as the PV solar-assisted heat pump (PV-SAHP) system, is presented. Comparative performance tests were conducted through an experimental rig under two different working conditions of the PV/T collectors: with and without glass cover. The energy performance in terms of PV/ photothermic conversions and refrigeration cycle was compared in typical winter days of the temperate climate zone in China. It was found that with a single glass cover, the exergy efficiencies of PV/photothermic conversions and overall PV/T conversion were, respectively, 12.83, 5.26, and 18.09 per cent, and the heat pump coefficient of performance (COP) was 4.85. Without the glass cover, the exergy efficiencies and COP were 13.36, 3.04, and 16.40 per cent, and 3.41, respectively. The results imply that although the presence of the glass cover leads to a small reduction in the PV exergy efficiency, it is able to improve considerably the photothermic exergy efficiency, the overall PV/T exergy efficiency, and the COP of the PV-SAHP system in winter.