Abstract: "Photovoltaic + energy storage" projects can be required in response to the development plan of the grain industry. This study aims to explore the operational performances of the photovoltaic-ground source heat pump system in grain flat warehouses during the summer. Four major ecological zones of the grain storage were taken as the North, Central, Southwest and South China, represented by the typical cities of Tianjin, Ganzhou, Kunming and Zhuhai. The prototype was taken as the No. 1 grain flat warehouse of Ganzhou Branch. TRNSYS software was used to set the materials and then build the model of the grain warehouse. The hourly cooling load of the grain warehouse in summer was simulated and then calculated with the design temperature and humidity of 15 ℃ and 60%, respectively. According to the maximum of the hourly cooling load, the equipment selection and matching of the photovoltaic-ground source heat pump system were carried out for the different grain storage ecological zones. After that, the photovoltaic-ground source heat pump system was built in the grain flat warehouse in the TRNSYS software. The temperature and humidity were simulated inside the warehouse. The performance of the photovoltaic system on the roof was evaluated to combine the ground source heat pump system. The results show that the photovoltaic-ground source heat pump system in the grain flat warehouse was reduced the temperature of the warehouse to the range of (15±1) ℃ within 10 h. The relative humidity was maintained at approximately 67%, fully meeting the requirements of the low-temperature grain storage. The better performance was achieved in the photovoltaic systems on the roof and the energy storage devices in the four grain storage areas. There was the photovoltaic power generation efficiency of about 20%. The accumulated surplus electricity was the highest in Kunming warehouse, thus reaching 55.80 MW·h. The lowest was observed in Zhuhai warehouse, at 0.31 MW·h. There was the normal air conditioning load power of the rest grain warehouses during the entire cooling season, except for the Zhuhai warehouse. The hourly power was basically stable at 10 to 18 kW. The Zhuhai warehouse in the South China grain storage ecological zone shared a relatively high proportion of the full-load operation time of the heat pump unit, with the Energy Efficiency Ratio (EER) decreased from an initial value of 4.15 to 2.54. The sufficient photovoltaic power supply was necessary for the continuous power supplementation from the grid. At the same time, the soil temperature in the Zhuhai warehouse also increased by 20 ℃, due to the continuous heat discharge to the soil. The highest soil temperature was found in southern China, unsuitable for the single ground source heat pump for air conditioning cooling. Therefore, the cooling towers should be used to assist in the heat dissipation during actual operation, in order to suppress the soil temperature rise. These system was no suitable for the grain storage ecological zone in South China. While the grain storage ecological zone in North China shared the highest contribution rate of the solar energy and the best system matching. This finding can also provide a strong reference for the engineering design of the photovoltaic-ground source heat pump system in the grain flat warehouses in different grain storage ecological zones.