Recycling solar panels: A new challenge for going green

Solar energy is a key factor in dealing with climate change but the sector’s rapid development is causing a technological problem – what do you do with broken, elderly or ineffective solar photovoltaic panels? Landfill is not an option, especially given the presence of toxic chemicals such as the carcinogen Cadmium. A fast technological recycling learning curve has resulted, raising major implications for businesses, consumers and politicians.

Devised as a linear solution to energy problems by providing inexpensive renewable energy, little consideration was given to the eventual need to dispose of unwanted and surplus panels, and the materials they contain. The size of the problem is now becoming apparent. The first generation of solar panels are now reaching the end of their lives, while yet more are being upgraded. The International Renewable Energy Agency (IRENA) indicates that by 2030, over ten million tonnes of solar panels will be thrown out every year worldwide, rising to 78 million tonnes by 2050.

Solar panels are complex products, involving silicon semiconductors covered in plastic, placed between glass and a back sheet surrounded by an aluminium frame. Copper wiring is used to link up groups of panels. Other materials used in the manufacture of panels include tin, lead, cadmium and silver. Existing recycling systems involve removing the metal frame and shredding the panels, while secondary chemical processing and electrolysis is used to separate the various metals, silicon and glass enabling a proportion to be reused.

In 2017, Veolia developed its first photovoltaic solar panel recycling plant at Bouches du Rhone. The plant currently deals with 4,000 tonnes of materials annually, deconstructing the panels and sending most of the materials for reuse. Plastic is used as fuel in a cement works, aluminium is sent to a refinery while two thirds of the glass is reused in glass making.

Å five year EU research project costing €4.8 million began in June 2021 exploring methods of recovering all solar panel elements including silver on an industrial scale. ReProSolar is led by Veolia Germany and involves production plants at FLAXRES in Dresden and Rosi Solar in Grenoble. New innovative processes are being utilised. Chemical processes allow silver threads to be removed from photovoltaic panels and turned into a solid material, while additional processing methods enables the recovery of high purity silicon that can be reused in new panels or EV batteries.

“Our process is based on a new delamination technology which is able to separate photovoltaic cells efficiently from the glass plate. Innovative physiochemical processes then enable the recovery of all materials without PV modules having to be shredded,” explains Antonine Driancourt, project manager at Veolia Umweltservice, an energy services company.

Obtaining high purity silicon is seen as crucial since this could make a major difference to the level of demand for raw silicon, as well as the ultimate costs of producing solar technology. Research underway in Korea has indicated that recycled silicon panels could prove to be more energy efficient. The Korean Institute of Energy Research is working on a non-destructive method of recycling solar panels to create high performance solar cells. Their technique is suitable for both undamaged and damaged panels, resulting in 100% retrieval of glass, 80% of other materials and refined silicon from groups of 72 panels being compressed into six inch crystal ingots and wafers. The resultant recycled cells using these wafers possess an energy efficiency rating of 20.52% compared to normal solar cells at 15%.

The ultimate target of creating a total circular economy is still remote. Approximately 90% of solar panel material possesses the potential for recycling through existing measures. Many of the most valuable elements within a panel such as tellurium and indium are at present economically unviable to recovery according to waste management company Remondis. The quantities used in each panel are too small for economic extraction. It is not just a matter of recovering and reusing materials, consideration also has to be given to the C02 emissions created during those processes.

“Recycling solar panels is a constantly improving process that lead to the supply of low carbon embodied materials into domestic industries,” comments Clive Fleming of Reclaim PV Australia. “Improving the energy supply to power equipment used to recycle is part of the optimisation process, as are advances in data capture for material flow and process efficiency to deliver much needed knowledge to support emerging industries to use these materials. Additionally, technology can allow us to study the chemical composition of the panels as reference markers to work out how to use more recyclable materials in solar panels.”

Creating a circular economy could also impact on material sourcing issues. IRENA has indicated that solar power production has to reach more than 8,000 GW by 2050, representing an eighteen fold growth rate in order to enable worldwide energy systems compatible with international climate targets. Higher demand for metals like copper, lead plus rare materials like tellurium and indium to create thin film cells will result. IRENA indicates that much of the demand could be met through recycling and reusing existing materials as long as early action is taken to create the required institutional groundwork.

Legislation is increasingly being imposed to require solar panel producers to finance collection and recycling systems. In the US, Washington State requires manufacturers to fund collection systems from 2023, while in Europe, the latest Waste from Electrical and Electronic Equipment (WEEE) directive requires producers to assume all responsibility.

The complex nature of solar panel recycling is costly. The Harvard Business Review has reported that in America, it currently costs $20-30 to recycle one panel while sending that same panel to landfill costs $1-2. Elsewhere figures are scarce as the industry is still coming to terms with the implications. Producers faced with legislative demands to deal with the problem will invariably seek to pass on many of the costs to end users – consumers and businesses. Improving the recycling of solar panels is becoming imperative, to ensure that all components and materials can be recycled or reused efficiently and sustainably.