| A hybrid Photovoltaic/Thermal (PV/T) solar system integrates photovoltaic and solar thermal technologies into one single solar energy device, with dual generation of electricity and heat energy. The aim of the present study is to evaluate the potential for introduction of the PV/T technology into northern China. For this purpose, outdoor experiments were conducted on a prototype of an unglazed PV/T water-heating system from November 2009 to August 2010. The thermal and electrical performances were investigated under the climatic conditions of Beijing. A mixture of propylene glycol-water was used as the heat removal fluid to prevent water from freezing during the coldest months. An economic analysis of the system was then carried out, using the discounted payback method. The analysis was then followed by a sensitivity study. The influence of parameters such as governmental financial subsidies, energy prices, PV modules cost and conversion efficiency etc. were studied.The experiments showed that the technical performances were strongly related to the climatic conditions and the supply temperature of the cooling fluid. The daily thermal and electrical efficiencies were found ranging between 27-75% and 5-11% respectively. In winter, the thermal performances were limited by the low temperatures reached by the PV modules, though they could be enhanced with low fluid starting temperatures. For domestic hot water applications, the system could annually produce about 790.66 kWh of thermal energy and 100.32 kWh of electricity.The economic analysis revealed that for such application, the hybrid system is not economically attractive with the current Chinese market and energy prices. However, considering the continuous commitment of the Chinese government towards policy development in the renewable energy sector, and technologicalimprovements like the increasing cost-effectiveness of PV cells, PV/Thermal technology may become economically viable in the near future. |
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