Solar Panel Recycling

Solar panels have had a rapid increase in popularity which is great for reducing global carbon emissions, but they have a finite lifespan and are now predicted to generate a massive 60 million tonnes of waste by 2050. Without dedicated solar panel recycling facilities, this waste could end up in landfills creating new environmental issues.

The good news is that solar panels can be recycled! However, this is a complex process. Solar panels are recycled by first separating them into their various components which mostly consist of aluminium, glass, and silicon. These materials can be broken down and used again, either to make future solar panels or in other applications.

Silicon-based and thin-film solar panels are recycled in different ways. It is estimated that if we were able to completely reuse the materials within solar panels, the total greenhouse gas emissions associated with solar panels would reduce by 42%.

Silicon-Based Solar Panels

---

Material/Component	Percent Recovered Through Recycling
Glass	95
Metal	100
Encapsulating Plastic	0
Module hardware	80
Silicon	85

Silicon-based solar panels are typically made of entirely recyclable materials. Recycling them starts with disassembly into their separate material components – however this isn’t a straightforward process.

Photovoltaic (PV) modules have a complex multi-layered structure that is designed to be robust and weatherproof for many years. This makes them difficult to take apart at the end of their life.

The recycling process can broadly be broken down into three steps:

1. Removing the external components: Removing the glass cover and aluminium frame is the easiest part of the recycling process. Recovered aluminium frames are remoulded for future solar panels, and the glass panes are typically ground down for further processing.
2. Unsticking the module: The trickiest part of the process is removing the encapsulating plastic that holds the PV module together. Organic solvents can be used but this option generates large amounts of hazardous waste. More commonly, thermal processing is used to evaporate the plastic off the module at a temperature of 500°C. This method uses a lot of energy, but the melted plastic can be used as a heat source for future thermal processing.
3. Separating the semiconductors: Once the cell has been un-stuck, the remaining materials within the PV cells can be recovered. The silicon wafers are etched with nitric acid to leach the metals. The metals are separated through an electric extraction method and the silicon is ground down and smelted into a reusable slab.

New methods for recycling silicon-based solar panels are in development with the hope of achieving an easier process that yields higher efficiencies at each step.

Thin-Film Solar Panels

---

Material/Component	Percent Recovered Through Recycling
Glass	90
Semiconductor materials	95

Thin-film solar panels are recycled with a more aggressive approach to break them down into their components.

1. Removing the lamination: Thin-film solar panels are first put into a shredder, followed by a hammermill, to break apart the lamination that holds the materials together. This process reduces the solar panel into particles which are no bigger than 4-5 mm.
2. Separation: The resulting mixture contains both solid and liquid materials. A large rotating screw separates these by keeping the solid parts rotating within a tube whilst the liquid is allowed to drop though into a collection container. Acid and peroxide are used to remove the films from the glass.
3. Collection and purification: The collected liquids contain metals which are purified via a precipitation and dewatering process. Metal processing is then used to completely separate the semiconductor materials, which typically include cadmium telluride (CdTe) or copper indium gallium selenide (CIGS). Meanwhile, the solid materials are put on a vibrating surface to remove any interlayer materials, and the remaining glass is washed thoroughly with water.

How Much Does It Cost To Recycle a Solar Panel?

---

It is currently estimated to cost between $15 and $45 to recycle a silicon-based PV cell in the US. This cost refers to factors such as the energy and labour used in the recycling process.

The cost of solar panel recycling is expected to decrease as more dedicated recycling facilities are built and the processes involved become more efficient.

Solar Panel Lifespan

---

The average lifespan of a solar panel is 25 to 30 years, though many continue to work far beyond that. Their long lifespan is in part thanks to their lack of moving parts, meaning very little maintenance is required to keep them running for a long time. The efficiency of solar panels drops by around 6 to 8 percent after 25 years and continues to slowly decrease as age increases.

Commercial solar panels were first rolled out in the late 1990s to the early 2000s, which is why we are now starting to face the issue of having to dispose of solar panels.

This issue is furthered by the recent surge in solar panel installations. Many countries and world organisations have set targets for solar energy generation leading to an increase in solar panel manufacturing. Additionally, as technology rapidly improves we are beginning to see people choosing to upgrade their solar panels before they reach their expected lifespan, creating more waste.

 

More Resources

---