Environment: ENEA patent to recover useful materials from photovoltaic panels at the end of their life

ENEA has patented a new process with low energy consumption and reduced environmental impact for the recovery of the main components of photovoltaic panels in crystalline silicon at the end of their life. The process allows to separate the useful materials, such as polymeric layers, electrical contacts, cells and glass, and to dispose of the rest safely through the minimal and localized ‘softening’ of the polymer layers through the heating of the panel and the subsequent tear-off detachment ‘. “The exponential increase in waste made up of photovoltaic panels at the end of their life has made it extremely urgent to address the problem of their management, even in the face of national and European laws that impose strict rules”, underlines Marco Tammaro, head of the Reuse Technologies Laboratory , Recycling, Recovery and enhancement of Waste and Materials and inventor of the patent together with entrepreneur Patrizia Migliaccio.

The invention starts from the ‘layered’ structure of the crystalline modules, consisting of a protective glass layer, then a thin layer of polymeric material, Ethylene Vinyl Acetate (EVA), then the silicon cells, metal electrical contacts, a second layer of EVA and a rear support surface, generally in polyvinifluoride (PVF); all enclosed in an aluminum frame. In fact, therefore, to recover the components it is necessary to ‘untie’ them from the EVA layer, which acts as a glue between the various layers. With this process the layers are mechanically ‘torn’, after the “targeted” heat treatment, so as to be able to recover the polymeric layers, the electrical contacts, the cells and 100% of the glass and the backsheet (in PVF), the EVA layer.

“With this process we avoid: the risk of degradation of materials, useless waste of energy and considerably reduce dangerous gaseous emissions. Furthermore, the necessary plant engineering is simple, suitable for continuous treatment and highly automatable, without the need for a controlled atmosphere through the use of specific gases “, adds Tammaro.

In technical detail, the patent aims to exploit the softening, minimal and localized, just sufficient to detach the polymeric layers to carry out a process in a continuous and automated mode. The invention proposes to heat the panels as they advance on a conveyor belt and to detach the polymer layers by means of a tear-off action, because the latter easily lends itself to process automation. The process easily allows the continuous processing of photovoltaic panels regardless of the different characteristics of the polymeric layers (thickness and types), and to which different minimum detachment conditions correspond.