Abstract: In an apparatus for collecting and storing solar energy, in order to improve the efficiency while maintaining a simple structure, a storage container is divided horizontally into a smaller upper water volume and a larger lower water volume by means of an intermediate bottom, and a device for attaining thermal equalization between the upper volume and the top of the lower volume is provided. This device is preferably embodied by a pump, which draws water from the upper volume and delivers it to the lower volume, and for volumetric equalization, a line penetrating the intermediate bottom is provided.