PV Integrated Heat Pump Technology

Hong Kong, a densely populated city in the sub-tropical zone, has a great potential of applying solar energy in hot water and electricity generation. In Hong Kong, most buildings rely on conventional water heaters for hot water supply, with fuels like town gas, liquefied petroleum gas and electricity. This has raised concerns about undesirable energy conversion effectiveness, greenhouse gas emission, and occupancy safety. According to the energy end-use data (1991-2001) published by the Hong Kong Government, direct hot water production consumes about 5% of the total energy use in the city, and 22% when considering only the domestic sector. Since 2005, the Hong Kong Government is targeting at achieving by 2012, 1-2% of the overall energy use to be from renewable energy. At this end, the PV-integrated heat pump technology can be an innovative and practical substituent for the conventional water heaters. This advanced, energy-efficient concept embraces multi-discipline technologies and can be seen as a sensible integration of the photovoltaic/water-heating (PVW) and solar assistant heat pump (SAHP) technologies.PVW technology refers to the integration of PV module and solar water-heating collector in one piece. The rationale behind the hybrid concept is that a solar cell commercially available converts solar radiation to electricity with peak efficiency ranged from 6 to 15%, depending on the specific solar-cell type in use. Most of the absorbed solar-energy is converted as heat, leading to an increase in the cell working temperature and subsequently a drop in electrical efficiency. By cooling the PV module with a stream of water, the electricity yield can be improved. At the same time, the heat pick-up by the water stream can be used to support services hot-water supply. However, in practice there is often a temperature mismatch between the PV-cooling and water-heating demands. When water in a solar storage tank is not hot enough to directly support the heating demand, it can be alternatively used as a heat source to serve the heat pump evaporator, and here comes the photovoltaic solar-assisted heat pump (PV-SAHP) technology.The objectives of project are:To study, via literature survey and experimental work, the opportunities and barriers in introducing PV-SAHP technology in Hong Kong; andTo predict through computer analysis, the optimized energy performance of this advanced hybrid system when applying in Hong Kong, as compared to the more conventional or alternative design options.