Transient simulation and life cycle cost analysis of a solar polygeneration system using photovoltaic-thermal collectors and hybrid desalination unit

Recently, water scarcity has been intensified in arid areas because of depletion of freshwater resources, reduction of rainfall, population, and urbanization growth. Therefore, the need to use desalination systems has increased in these areas. On the other hand, the increase of building energy consumption for achieving enhanced thermal comfort has become a global crisis due to the depletion of fossil fuel resources and related environmental problems. In this study, a small-scale solar polygeneration system using photovoltaic-thermal solar collectors and hybrid humidification-dehumidification and reverse osmosis desalination units is proposed to supply the electricity, domestic hot water, space heating, and freshwater demands of a one-story house. The dynamic simulation of the system performance in the Hot-Dry climate zone is done using the TRNSYS-MATLAB co-simulator. The results indicate that using the thermal and electrical energy generated by the proposed system, the building annual energy consumption for providing domestic hot water, and space heating demands reduce 100% and 27.2%. The increase of the annual solar fraction of domestic hot water and space heating, because of using the electrical energy generated by the system, is 11.3% and 15.6%, respectively. The electricity and freshwater demand of the building is completely supplied by the proposed system and the excess electricity is sold to the grid. Economic analysis indicated that fuel saving cost of 29479 $ and water saving cost of 23779 $ are obtained during the life cycle of the system and the payback period is 3.75 years. The results show that the considerable energy savings are achieved using the proposed solar polygeneration system for providing the required electricity, heating, and fresh water demands of the residential buildings.