Environment: Recycling photovoltaic panels’ end-of-life materials

ENEA has patented a new low energy consumption and reduced environmental impact process for the recovery of the main components of crystalline silicon photovoltaic panels at the end of their life. The process allows to separate useful materials, such as polymeric layers, electrical contacts, cells and glass, and to safely dispose of the rest by softening polymer layers through heating the panel and subsequent mechanical detachment'.

The exponential increase in waste of photovoltaic panels at the end of their life has made it extremely urgent to address the issue of their management, also in compliance of strict national and European rules ", Marco Tammaro, head of the Reuse, Recycling, Recovery and Valorisation of Waste and Materials  Laboratory and inventor of the patent jointly with Patrizia Migliaccio, pointed out.

The invention is based on the 'layered' structure of the crystalline modules, consisting of a layer of protective glass, 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 order 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 a "targeted" thermal treatment, to recover polymeric layers, electrical contacts, cells, all the glass, the PVF backsheet and the EVA layer.

“ With this process the risk of degradation of materials and useless waste of energy are avoided and dangerous gaseous emissions are considerably reduced. In addition, 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", Tammaro said.

Technically, the patent uses minimal and localized softening -sufficient to detach the polymeric layers- to conduct a continuous and automated process. The invention proposes to heat the panels as they advance on a conveyor belt and detach the polymeric layers by means of a tear-off action, since the latter is suitable for process automation.

The process allows a continuous processing of photovoltaic panels regardless of the different characteristics of the polymeric layers (thickness and types), corresponding to different minimum conditions of detachment.

For more information:

marco.tammaro@enea.it
Patent N. 102017000033488 mise.AOO_PIT.REGISTRO UFFICIALE.U.0180568.10-07-2019