A novel triple-tank solar water heating system with an additional makeup water tank and the corresponding control strategy were proposed based on the traditional dual-tank solar water heating system. The objective is to utilize this water tank to store solar energy to heat the makeup water under high and low solar radiation， thereby improving the solar fraction and reducing the operation time of the auxiliary heater. To evaluate its performance， a TRNSYS simulation model was established and validated by the results obtained from the experiments. Based on the model， the operation performance of the proposed system and its influencing factors were analyzed. The results showed that the annual solar fraction of the proposed system was increased by 22.42% compared with that of traditional systems. Simply increasing the volume of the make-up water tank would not necessarily result in the increase of the annual solar fraction. Therefore， when selecting the optional volume of the makeup water tank in practical applications， the annual solar fraction and initial investment should be comprehensively considered. Moreover， it was found that the proposed system could achieve a higher solar fraction than traditional systems under different water usage modes. In addition， an economic analysis was conducted for applying the proposed system in a residential building in Changsha. The results showed that annual operation cost could be decreased by 18.31%， and the payback period was 0.66 years.