A team of Chinese scientists has developed a new method to recover and recycle salvageable materials from discarded solar panels.
The novel technique uses a chemical compound known as dibasic ester to separate individual components from one another, without damaging and breaking the desired solar cells.
In March 2023, the China Academy of Sciences-based research unit published its findings in the journal, Clean Technologies and Environmental Policies, describing the method as a non-violent and controlled process.
The photovoltaic (PV) industry is one of the fast-growing in the world, with roughly 168 gigawatts of new solar PV units installed in 2021, according to data released by Statista.
It accounts for roughly 3.6 per cent of the Earth’s energy production, falling behind only wind and hydro in terms of renewables.
However, solar panels have a short lifespan and are only effective for about 30 years before they need replacing. It’s not impossible to recycle retired PV units, but the process is time-consuming and expensive.
Each panel is constructed from a mixture of aluminium, plastic, glass, silicon and other hazardous chemicals.
Despite the recyclability of most of its core components, the process is machine and energy-intensive, meaning most disowned solar panels inevitably make their way to landfills where some of their toxic materials, such as cadmium and lead, leach into the environment.
Lead scientist, Wang Dong, and his team say they have found a way to separate glass and other PV materials from their back sheets with a “swelling” process where old panels are treated with dibasic ester (DBE), a chemical compound commonly used in lubricants, paints, and solvents.
According to the team, DBE is a low-toxicity, recyclable swelling agent capable of dissolving most resins.
Wang claims the DBE solvent effectively penetrated the area between the glass and the solar panel’s back plates while preventing unwanted air from entering the gap.
Each PV panel is then subjected to an ultrasonic field that further encourages the separation process.
The system can be filtered so that a mixture of glass and solar cell composites remains, which can be run through a sieve until recyclable glass materials are removed from the mixture, leaving behind undamaged and reusable solar cells, say Wang and his colleagues.
Unlike other separation methods, Wang’s technique does not require intensive thermal processes that create a fluoride by-product.
The team is confident its novel DBE-based separation system can make resource recovery in the PV industry a less tedious and cost-effective endeavour, but the true feasibility of the process would be understood with scaled-up testing.