Floating tracking cooling concentrating (FTCC) systems

The photovoltaic technology is limited by costs, by the availability of spaces for photovoltaic fields and by the storage problems. The solution suggested in this work is the use of artificial basins or small lakes for installing PV floating plants with the following characteristics: a tracking system around the vertical axis, a panels cooling system achieved with water sprinklers and a set of reflectors that, by concentrating the radiation, increase the energy harvesting. We call these plants FTCC, the acronym of Floating, Tracking, Cooling, Concentrating. Additional benefits are possible using hydroelectric basins in particular when they are equipped, as often happens, with pumping facilities. In these structures, the existing pumping devices allow to store the energy produced by the FTCC avoiding energy dispersion problems and the electric grid stress. Three FTCC system solutions are presented and discussed theoretically and experimental results are also discussed. They are characterized by different levels of geometrical concentration, Cg: <1.5, ≈2 and ≈20. In particular the first two systems use flat reflectors, whereas the third one uses parabolic mirrors. An important issue that arises when these systems are designed and operated is the uniformity of irradiance on the PV surface. This can be reached by means of an effective sensing and tracking of the system taking into account the relative position of sun and reflectors, as well as the acceptance angle of the concentrators. A first plant of 200 kWp based on these concepts is completed and grid connected in Suvereto - Livorno (Li Italy); another 30 kWp pilot plant has been built nearby Pisa (Italy).