Life Cycle Assessment of CdTe PV Module Recycling

The photovoltaic industry considerably increased in the last years. Thin film technologies have grown at an even more significant rate than conventional silicon solar technologies. A market share of about 20 % for thin film solar modules is forecasted for the year 2020 and worldwide measures to increase the production capacities of photovoltaic manufacturers are recognized. Besides the increasing implementation of photovoltaic’s on the market it is strongly important not to lose sight of possible end-of-life strategies for used PV modules, like take back systems and recycling options. Due to the long life expectancy, today’s returns of used PV modules are relatively low, but it is expected that there will be a significant increase from the year 2020. PV manufacturers already identified the need for research on further treatment options of used PV modules and to develop technology specific recycling processes. Based on advanced recycling procedures, most materials used in PV modules can be returned on the market as valuable materials, or in case of plastics, energetically recovered. Regarding thin film technologies, the recycling of used modules could also provide an additional source of rare metals like tellurium or indium to satisfy the increasing demand of these materials on the market. For ecological purposes, the recycling of modules can furthermore contribute to a reduction of the environmental profile of the whole module life cycle. Using the method of Life Cycle Assessment (LCA), these environmental benefits due to the recycling of PV modules can be quantified. At Chair of Building Physics (LBP) a Life Cycle Assessment study was carried out to evaluate the environmental profile of the recycling of CdTe modules. Based on latest industry data, the study presents LCA result of an already applied recycling process of CdTe solar modules. Within this study a detailed LCA model of the recycling is built up including the processing of used modules, the recycling and energy recovery of materials as well as the further treatment and disposal of solid and liquid wastes. The study showed that the recycling of materials would contribute to a significant reduction of the environmental profile of end-of-life of CdTe modules. In total, the recycling of outgoing materials would reduce the Primary Energy demand in the End-of-Life from 81 MJ/m² to -12MJ/m² (reduction from around -93MJ/m²) and in terms of the Global Warming Potential from 6kg CO2-equiv./m² to -2,5 CO2-equiv./m² (reduction from around -8,5 kg CO2-equiv./m²). The paper gives an overview on the approach of the study, discusses the main outcomes and analyses the significance of recycling in relation to the environmental profile of the production and total life cycle of CdTe modules.