Abstract: Solar seasonal water thermal energy storage systems can realize "using summer heat in winter" in hot-summer and cold-winter regions and significantly reduce carbon emissions of traditional heating methods. However, they have problems such as difficult output temperature regulation and temperature drop in the middle and late stage of heating. To meet stable heating needs, a water - source heat pump (WSHP) should be coupled for flexible temperature adjustment. This paper takes a three - story large building in Wuhan as the heating object and constructs a multi - source heating system that combines photovoltaic/thermal (PV/T) collectors, seasonal water thermal energy storage, and a WSHP. A whole - year dynamic simulation model is established to deeply study the system's comprehensive performance from three aspects: energy efficiency, economy, and heating stability. It is also compared with a single PV/T seasonal water thermal energy storage heating system and a PV/T system coupled with an electric boiler. The results show that the PV/T system coupled with a WSHP has the best comprehensive performance. Its annual average seasonal energy efficiency ratio (SSER) is 7.537, the life cycle cost (LCC) is 1.4283 million yuan, and the root mean square error of the heating inlet water temperature is 1.321. Furthermore, the Hooke - Jeeves algorithm is used to optimize the area and tilt angle of PV/T collectors, the volume of the hot water storage tank, and the rated heating capacity of the heat pump. After optimization, the system's SSER increases by 4.59%, and the LCC is reduced by 8.89%, indicating a significant optimization effect. This research can provide theoretical basis and engineering guidance for the design and optimization of solar seasonal thermal energy storage heating systems for large buildings in hot summer and cold winter regions.

Key words: seasonal thermal energy storage, PV/T system, water source heat pump, TRNSYS, parameter optimization