PROJECT DESCRIPTION
BACKGROUND
Photovoltaic panels need to be disposed of correctly at the end of their life. Failure to do so leads to pollution by heavy metals (lead and cadmium), loss of conventional resources (aluminium, glass and silicon), and the loss of rare and precious metals (silver, indium, gallium and germanium). Photovoltaic waste volumes were low at the outset of this project. However, first generation solar panels are reaching the end of their productive lives. By 2020, photovoltaic waste was expected to increase significantly. By 2050, it is estimated that some 10 million tonnes of end-of-life solar panels will have to be treated and appropriately disposed of in Europe. The European Commission included end-of-life photovoltaic panels in the Waste Electrical and Electronic Equipment (WEEE) Directive, which promotes the development of innovative processes for the recovery of secondary raw materials such as glass, plastics and metals. The recycling sector must now respond to the challenges and opportunities presented by this relatively new waste stream.
OBJECTIVES
PHOTOLIFE aimed to reduce the lifetime environmental impact of solar panels by constructing a pilot treatment plant for spent panels. Using relatively simple and mild physical and chemical operations, the project's goal was to achieve a wide level of recycling and recovery of valuable raw materials in line with the WEEE Directive. This innovative process, moreover, would enable the simultaneous automated treatment of the major types of photovoltaic cells, including monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride (CdTe) and copper indium gallium selenide (CIGS). This would involve a hydrometallurgical approach, employing physical operations, such as crushing, to avoid energy consumption, and chemical operations using an aqueous/organic solution to detach the ethylene vinyl acetate (EVA) encapsulant, a first for the nascent solar panel recycling sector. The project team expected to recover a significant amount of valuable raw materials – including the different metals contained within the photovoltaic cells as well as any metal frames, glass, plastics and electronic equipment used in the solar panel systems. It aimed to characterise the different outputs of the recycling process, determine the overall economic feasibility of the pilot plant (including through potential use of recovered materials) and put in place short and long-term management strategies for implementing the system.
RESULTS
The PHOTOLIFE project set up a pilot plant capable of recycling 200 tonnes per year of solar panels at coordinating beneficiary ECO RECYCLING's premises in Civita Castellana, Lazio. The panels are disassembled by removing the aluminium frame and the electric cables, before being ground, crushed and sieved in a crushing unit with a capacity of 150 kg per hour. The intermediate fraction is pre-treated with chemical products and the glass mass is extracted and ethylene vinyl acetate (EVA) removed. The coarse fraction is reintroduced in the initial phase and the cycle is repeated for additional glass recovery. The project also tested a hydro-metallurgical approach to the treatment of the resulting fine fraction. This involved the extraction of metals from inverters and junction boxes in a plant established by the EU FP7 'urban mining' project, HydroWEEE. The pilot line processed a total of 2.78 tonnes of silicon-based, CdTe and innovative (CIS/CIGS) solar panels, resulting in the recovery of 71.7% of glass per tonne of processed material, less than the expected yield of 80%, but an acceptable return. This glass was of a high enough quality to be resold. The chemical section of the pilot plant works at low temperature, which means it does not modify the internal structure of the polymeric materials present in the solar panels; mainly Tedlar and EVA. These two plastics can be reintroduced in the market as secondary raw materials. Tests of the hydro-metallurgic process for extracting metal concentrates from the fine fraction at the HydroWEEE plant produced the following results: 0.43 kg of metal concentrate recovered from 72.5 kg of silicon-based panels (achieved target yield); 0.09 kg of metal concentrate (aluminium, tellerium and zinc) recovered from 56 kg of CdTE-based panels (below target yield). Based on its results, the project calculated a payback time of just over 3 years for a full-scale solar panel recycling plant using the methods demonstrated. The beneficiary has found an investor to establish a plant with a capacity of 5 000 tonnes per year and it has signed a memorandum of understanding with the Municipality of Genoa for the collection of used solar panels. The project estimates that 20 people would be needed to run a plant of 5 000 tonnes per year. With more than 2.5 million tonnes of solar panels at their end-of-life by 2035, up to 200 000 tonnes per year of solar panels may need to be recycled in Italy alone. The development of this photovoltaic panel processing plant contributes to the objectives of LIFE's sub-programme for Climate Action and to the implementation of the EU Roadmap for moving to a competitive low carbon economy in 2050. This is line with the WEEE Directive and the Circular Economy Action Plan. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
