Image: REUTERS / Jean-Paul Pelissier

We still see solar panels as a 100% sustainable solution. While it is true that they are excellent for generating renewable energy, photovoltaic panels have a drawback that we often ignore: they are very difficult to recycle.

One drawback which does not make them less attractive is only a problem that needs to be resolved, with new manufacturing or recycling systems.

Photovoltaic panels contain solar cells, including heavy metals such as lead and cadmium, so it is dangerous to throw them in the landfill.

Unfortunately, many panels are often found there after they have passed their useful life. Work is underway to promote large-scale recycling of solar panels in a safe and cost-effective manner.

What are solar panels made of?

One of the most important components of a solar panel is silicon. After oxygen, silicon is the second most abundant element in the crust of our planet. There are three main methods for converting silicon into panels.

  • The monocrystalline solar panels they are the most efficient and the most expensive. Manufacturers cut individual wafers from a large block of silicon and then affix them to the panels. This intensive process produces the highest quality and most efficient solar panels.
  • the polycrystalline solar cells They are made by melting many crystals of silicon and then fusing them together in mass into a panel. These are bluish and are cheaper than monocrystalline panels, but also less efficient.
  • the amorphous silicon cells They are not very efficient, but they are thin and flexible. This viscous material adheres to metal, glass or plastic.

But cells alone cannot provide electricity. Power generation requires cables and a metal enclosure. Standard solar panels also include a glass cover on the front of the panel to protect against damage and temperature rises, reducing efficiency.

Lifespan of solar panels

When people invest in solar panels for their home or business, they often expect them to last forever. But current models lose 6-10% efficiency after about 10 years.

At 25 years of age, the drop in efficiency is 20%. However, high quality panels could last 30-40 years with reasonable efficiency and continue to operate thereafter, but not at full capacity.

Hence the importance of buying quality solar panels.

The challenge of recycling solar panels

In 2016, the International Renewable Energy Agency (IRENA) estimated that there were approximately 250,000 tonnes of solar panel waste worldwide. As more panels reach the end of their useful life, the agency expects that number to approach the end of their useful life. 78 million metric tonnes by 2050.

One of the problems is that solar panels are very large. They must be, because large areas are needed to collect enough sunlight. Solar panels therefore require many more raw materials, including glass, rare earths and heavy metals.

Unfortunately, you can’t just throw the signs in your trash. Toxic chemicals should be removed first, and this cannot happen without breaking the entire panel.

About 90% of most PV modules are made of glass. However, this glass often cannot be recycled due to impurities. Common troublesome impurities in glass include plastics, lead, cadmium, and antimony.

Dustin Mulvaney, professor of environmental studies in the state of San José.

Image: REUTERS / Jean-Paul Pelissier

Experts discussed the safety of signs at landfills. Some say it is safe enough, while others predict that toxic material will seep into the ground. But while the disposal of panels in landfills was safe, more waste is not a solution.

One possible solution is to financially finance the recycling of the panels. A large industry could be created around this sector.

The recycling process for solar panels

The hardest and most expensive part of recycling solar panels is separating their components. Once done, most of its parts are recyclable.

Recycling silicon photovoltaic panels involves heating them to 500 ° C to separate the silicon from the metal and material. The broken silicon pieces can be 85% melted and reused.

The thin-film panels are placed in a crusher and then in a hammer mill, until they are separated into liquid and solid materials. Recycling facilities use a rotating screw to separate the liquid.

After all the post-processing, about 90% of the glass elements and 95% of the semiconductor material can be reused.

But unless regulations on recycling solar panels are tighter and prices drop, many panels will continue to go to landfills. Some experts recommend that a fee be imposed on new solar panels which would be kept in a recycling and disposal fund. This could pay for the removal and recycling of the panels at the end of their useful life.

A second-hand market for old solar panels could also be interesting. After 30 years, a panel may have lost its effectiveness, but it still has life. Some buyers may be interested in paying for these used panels if they are still in use and the price is reasonable.

Which companies recycle solar panels?

European government regulations require owners of solar panels to recycle their panels. PV Cycle is probably the biggest name in solar recycling in Europe. In 2018, he opened a recycling plant, using robots to separate glass from silicon, metals and plastics.