The solar water natural circulation during operation exploits the natural phenomenon of fluid flow by temperature difference (density difference), also known as the beginning of the water heater. Thus is achieved naturally, without the pump (pump) continuous flow of the heated medium from the hottest point (solar panels) to the cooler (water tank) until the two points to obtain similar temperatures. To make this possible the coldest point should be higher than the hottest point and therefore all solar panels storage tank is always higher than the solar panels. (Where air bubbles generated in the closed circuit system performance is reduced)
The overall yield of the solar heater on the size and kind (quality) of the collecting surface in relation to the heat sink (which is the smaller raises higher temperature) and the ambient temperature, cloud cover and the efficiency of the heat insulation system.
It takes time and specific measurements to the water temperature not exceeding the boiling point and can not be steamed. For the economical operation of solar water heater both at reviving and the electric operation during the winter months is necessary reservoir to store water heating. For this reason and to protect the environment, manufacturers are studying systems with tanks as possible so smaller and more efficient solar systems. For these measurements laboratories issued on behalf of manufacturers into performance certificates systems.