Impacts of hot water consumption pattern on optimum sizing and techno-economic aspects of residential hybrid solar water heating systems

Hot water consumption pattern culture, appropriate sizing of solar water heating (SWH) systems, governmental policies and incentives on renewable energy projects, and climate conditions are factors that can affect the techno-economic and environmental performance of hybrid water heating systems. This paper aims to simultaneously include these factors in techno-economic modeling of hybrid water heating (HWH) systems. Different domestic hot water (DHW) consumption patterns are considered. The required hot water for space heating is calculated for a typical dwelling located in Shiraz, Iran. Electricity and natural gas water heaters are considered as auxiliary systems. The appropriate sizing of the solar system to achieve the desired techno-economic performance is obtained. The results show that the optimum ratio between storage tank volume and collectors field area to achieve up to 90% of solar fraction, does not exceed 0.08 m in all cases. By liberalizing the energy price, 80-90% of DHW consumption can be supplied by SWHs at a viable price. When the space heating is also included, the collector field area, storage tank volume, and solar fraction reach to 50 m2, 1.4-1.9 m3, and 50%, respectively, in most economic design where 42.7-45.3% lower price is achieved.