Characterization of End-of-Life Modules for Subsequent Delamination and Recycling

Abstract

The photovoltaic capacity installed worldwide exceeded the 1000 GW mark in 2022. There are currently still small amounts of end-of-life (EoL) photovoltaic (PV) modules that have to be disposed of or recycled. However, a strong increase is to be expected in the next few years, for which it is important to be prepared accordingly. As part of the PVReValue research project, the scientific and technical basics for a comprehensive layer-by-layer separation and recycling process for EoL PV modules are being developed and evaluated. In order to achieve a recycling rate of over 95 percent by weight, a holistic recycling process is to be developed, which consists of the following steps: (i) input characterization, (ii) component separation, (iii) further processing of the separated fractions, (iv) output characterization and (v) finding recycling or reuse routes of the output fractions. An innovative approach is chosen for the separation of the PV modules: The composite (multi-material laminate) is first separated into the three main fractions (1) backsheet, (2) encapsulation + solar-active semi-conductors and connections and (3) glass (as a pane) (compare Figure 1). In order to achieve this layered separation using mechanical delamination processes such as milling, water jet cutting or high-temperature sawing, it is necessary to thoroughly characterize the installed components in advance in terms of their thickness and material identity. For this purpose, several non-destructive and destructive analysis tools are first tested, which enable a quick and qualified determination of the layer thickness of the backsheet and the encapsulation material. These methods are evaluated in terms of time, cost, accuracy, and spatial and lateral resolution, as well as their suitability for the integration into an industrial separation process. Since many backsheets contain fluoropolymer layers (PVF, PVDF or F-coatings) that require special handling and separation during the recycling process, their possible presence must be clearly identified BEFORE the PV module is delaminated/separated. So far, molecular spectroscopic methods are the analysis tools with the greatest potential for delivering reliable results - provided that highly qualified evaluation software and databases are used.