Abstract
A design of a floating focusing system based on polymer films is proposed, in which water is the material for making the lens. This makes it possible to implement a focusing system of high optical power with minimal material costs, as well as with minimal energy consumption to ensure that the focusing system is pointed at the Sun, which is achieved due to zero (or close to it) buoyancy of the tunable element. It is shown that this approach, among other things, meets the concept of small green energy, which is focused on ensuring maximum independence of households from centralized energy supplies. It is taken into account that the energy consumption structure of a typical household is such that only a small proportion of consumption falls on appliances whose operation cannot exclude electricity consumption. Most of the energy consumption can be reoriented to energy sources that do not require the mandatory generation of electric current, which also determines the social significance of the proposed approach.