Converting sunlight into energy is probably the green method par excellence for electricity production. There are different systems for doing this – from the more traditional photovoltaic systems to thermodynamic ones that concentrate the sun’s light and exploit its heat to generate energy – but they all share a problem: dirt. When dust, pollen, limescale and bird droppings accumulate on the solar panels and mirrors (the latter being characteristic of thermodynamic power plants) the energy yield of the systems progressively decreases, making periodic cleaning interventions necessary which affect the cost of the energy produced. However, a team of Enea researchers believes they have the solution: a low-cost process that makes the mirrors and panels of solar systems self-cleaning, without compromising their reflective properties.
“The process we have developed allows us to address a problem that has been unsolved up to now thanks to a coating process that modifies the wettability of the mirrors, i.e. the ability to come into contact with water, preserving their optical properties and possibly performing a protective function with respect to to erosion and corrosion”, explains project coordinator Anna Castaldo, researcher at the ENEA Energy and Thermal Storage Laboratory and author of the patent together with colleagues Emilia Gambale and Giuseppe Vitiello.
The inspiration for this new technology – explain its inventors on the Enea website – comes from the automotive sector. In fact, the machines are designed to survive, and remain shiny, for years, despite constant exposure to the elements. The credit goes to the paints used to cover them, which allow frequent washing without causing wear. Hence, the idea of the Enea researchers: select the components of paints for automotive use with the suitable optical requirements, and use a low-pressure spray technique to transform them into a coating for the protection of mirrors and panels used in energy production solar.
“The line of products for which a change of intended use is proposed is already present on the market and the high volume of air and low pressure spray technique, known as HVLP, is a widely used technique as it is eco-sustainable, that is, free from problems linked to the presence of polluting propellants”, continues Castaldo. “This means that there is a well-established industrial supply chain that implements it, such as that of automotive paints, and that the process in its entirety is easily usable by the companies involved”.
The invention, as we mentioned, has already been patented, and is mainly designed for use in the coating of the solar mirrors of thermodynamic plants, most used in the production of energy for industrial purposes, and often located in semi-arid areas where solar radiation is high, but so is the presence of sand, dust and pollen which can quickly reduce the efficiency of the mirrors. However, the coating can be used to make all those sectors self-cleaning (and therefore more efficient) – such as photovoltaics, anti-ice and anti-frost systems, outdoor lighting – where modulation of wettability combined with transparency and resistance to bad weather is required. .