For solar hot water, what do the solar panels do when the tank is full of hot water?

For solar hot water, what do the solar panels do when the tank is full of hot water?

As the hot water comes into the tank it pushes colder water to the bottom of the tank (because hot water rises, so cold water must drop) where its only option is to go back into the solar panel to get hotter through heating. As this cycle repeats the water in the tank will get hotter and hotter until it reaches the system’s design temperature.