Improving the design method of a solar heating system considering weather uncertainty and system reliability

In the conventional design of a solar heating system (SHS), the auxiliary heater is sized according to the peak heating load without considering the combined heating of solar energy, which leads to an oversized auxiliary heater. Moreover, the commonly used simulation software for optimal design is generally based on typical weather conditions or average values, ignoring the uncertainty of weather changes and hourly system reliability. To accurately optimal the capacity of auxiliary heater under uncertainty and reliability, the concept of equivalent design capacity (EDC) of a SHS is proposed in this paper. EnergyPlus and TRNSYS are adopted to evaluate the system reliability of an office building, and the 20-year actual meteorological parameters are used to reflect the weather uncertainty. The results indicate that the auxiliary heater capacity can be reduced by 15.2% after considering the EDC, and the EDC could be further boosted by increasing the solar collector area. Furthermore, the EDC is mainly affected by the design reliability through the sensitivity analysis. The lower reliability the designers choose, the higher the EDC will be, but the increase will be smaller and smaller, which should be valued in the design of a SHS. (C) 2019 Published by Elsevier B.V.