The upright tank can keep the water at different temperatures. For example, it can heat the top water instantly and its special structure will prevent mixing of cold and hot water.
The tank is located inside the building, and so the connection pipe between the tank and water tap is very short. This means that hot water can be used instantly and cold water seldom flows out. Also, the hot water loses less energy than with a normal tank.
The heater collector and the water tank are separated, making the system fit perfectly within the building, without affecting the aesthetics of the building and the environment around.
Back up electric heater ensures that hot water can still be used in a day without sunshine.