Transient Performance and Distribution Strategy Analysis of Solar Water Heating Systems

The solar water heating system (SWHS) is one of the main ways to utilize solar energy. In this study, the design, transient performance, and techno-economic analysis of a hotel SWHS in Shanghai are carried out. Three distribution strategies are considered for the SWHS, which are small-scale distributed system (System I), medium-scale system (System II), and large-scale centralized system (System III). Transient performance simulation results show that starting frequency of the auxiliary heater is much lower in summer than that in winter. System III holds the highest annually average daily obtained heat per person (13.021 MJ/person) and the lowest annually average heat loss percentage (2.10%). System I has the highest annually average thermal efficiency, which is 48.05%. Cost of the collector accounts for more than 70% of the total investment of three types of systems. Payback period of the three types of systems is System I > System II > System III. When constructing the SWHS in Shanghai, the large-scale centralized system is suggested. This research provides a theoretical basis for the design, selection, and construction of the SWHS in China.