The heat collectors and the water tanks are connected perfectly, the heat which the panels collected will be stored in the water tank, it guarantees 24 hours per day to provide the hot water, and the system can work even under the -30 degrees. It can supply with a few tons even more water, is an ideal hot water supply system. It is applied to the big hotels, restaurants and other large places. 1: The water tank should be placed higher than the heat collectors, while the models are isolated types and the heat collectors are not pressure-enduring; The water recycled freely by the height difference between the water tank and the heat collectors. 2: The water tank should be placed lower than the heat collectors, while the models are isolated types and the heat collectors are pressure-enduring, the water is recycled by the water pump between the water tank and the heat collectors, the specific pressure-enduring models, please see the information of the pressure-enduring models on the web.