Optical methods to identify end-of-life PV panel structure

The aim of this work is to investigate the possibility of applying optical spectroscopy methods for the recognition and sorting of end-of life (EoL) photovoltaic panels (PVs) collected at WEEE pre-treatment plants, where they arrive, nowadays, without any label containing information about their composition and structure. EoL PVs belong to the category of layered waste containing hazardous materials, like fluorine in the backsheet, therefore implicating a proper treatment based on their composition, in order to reduce the environmental impact. The identification of the PV panel structure is fundamental to assess the next steps of the recycling process, which is strongly dependent on the constituent materials. Vibrational spectroscopy, commonly used to identify the materials composing waste products, is certainly capable of giving the compositional structure of EoL PVs. However, the identified procedure to recognize the multilayer structure requires a mechanical or chemical delamination of a representative piece of the EoL PV and the following optical spectroscopy analysis of each face of the delaminated layers. Despite this procedure employs cheap and easy to handle equipment, like portable spectrometers, it appears time consuming and not easy to be automatized in a WEEE pre-treatment plant. Therefore, we define more rapid methodologies suitable to be adopted in pre-treatments plants. We discuss the drawbacks of the proposed methodologies and we suggest, as a more efficient solution for the future, the labelling of the PVs put on the market (for example inserting RFID or QR Code tags) containing information on their structure and composition.