What happens to solar panels when it doesn’t work anymore?
Author: Darvin Tocmo Date Posted:25 February 2019
Solar panels are made to last. Barring damage from natural disasters or accidents, modern solar panels have an expected lifetime of 25-30 years, and some of the first commercially-available panels have crossed that milestone and are still operating almost as well as they did when new.
Nearly all solar panels in the world were installed after 2009, and come with a guarantee that they’ll produce at least 80% of their rated power output after 25 years. Most panels on the market will do better than that, producing about 85% of their rated output after 30 or 35 years.
Humanity has a two- or three-decade runway to learn how best to deal with solar panels at the end of their useful life, but by 2050, it’s expected solar panels will account for 60 million tons of waste. Recycling all the materials that go into making them is essential, because those 60 million tons of panels will represent nearly $16 billion invaluable resources, and some materials used are potentially toxic if discarded in a landfill.
We have the perfect proving ground: as the production of solar panels ramps up, there will inevitably be a need to recycle broken panels, duds, and panels destroyed by natural disasters. Now is the time for governments and the industry to set the standards for recycling the panels that can be used as the number of solar waste increases in the coming decades.
What materials go into making a solar panel?
The vast majority (over 90%) of solar panels that have been sold are made with crystalline silicon solar cells. These are the “typical” solar panels you might think of when you think of solar. Square-shaped solar cells with rounded corners joined together with electrical contacts inside an aluminum-framed glass-topped panel.
The layers include a frame made from aluminum, low-iron glass that covers the whole panel, crystalline-silicon solar cells sandwiched between two layers of EVA encapsulant (a plastic material), and a back sheet made of polyvinyl fluoride that provides extra protection from moisture, UV light, and temperature fluctuations.
The layers are fairly simple, and when combined together using heat to seal the encapsulant and bond it to the glass, form a very sturdy panel; built to last.
Toxic materials in solar panels
In a typical silicon solar cell, the amount of toxic chemicals is negligible, and tests done on these panels have revealed levels of toxic chemicals far beneath the standards set forth by the EPA.
Tests called “toxicity characteristic leaching procedure” tests (TCLP), are done to check for toxic chemicals that can leach into the environment from waste disposal. Studies that collect the results of these tests have shown (PDF links) that the panels have the potential to leach minimal amounts of lead, chromium, and barium, spread among the various components.
There’s no need to throw these things away, though. Solar panels are made up of valuable materials that can mostly be recaptured, and the industry has committed itself to discover the best way to recycle solar panels and either re-use or re-sell the components.
How much of a solar panel can be recycled?
Most materials that go into making a c-Si solar panel can be reclaimed through recycling processes. In the United States, the law that governs solar panel disposal is called the Resource Conservation and Recovery Act (RCRA), which applies to all solid waste.
Under the RCRA, it is currently legal to simply throw away solar panels like normal garbage, provided they’ve passed the aforementioned TCLP test. But again, the materials used to make the panels are valuable, so it behooves the industry to figure out how to reclaim the components for future use.
As is normal for most things related to environmental well-being, European regulators are leading the way, and have developed a set of standards for recycling solar panels, requiring manufacturers to take back their panels at the end of their lives at no charge to the owners, and send them to a recycling facility where the components are broken down, sorted, and re-sold to make new solar panels and other products.
Here’s a look at the current state of solar panel recycling in Europe:
Manufacturers that recycle their own panels
Following the EU regulations, Some solar companies across the world, have already begun their own reclamation programs in order to streamline the process as waste increases into the future.
Some manufacturers has its own proprietary process for reclaiming its cadmium telluride (CdTe) thin-film solar panels, which results in 95% of the semiconductor material and 90% of the glass available for reuse, either in new solar panels or other products. The company makes the recycling service available to its customers as part of its sales and service process. Recycling costs extra, unfortunately.
To perform the recycling, the manufacturer takes panels back from its customers, then puts them through a process that involves shredding, crushing, and treating the panels with a liquid process that helps to separate the component parts. Glass and laminate are separated and reclaimed in one process, and the resulting metal slurry is sent to a third party, who performs a process that results in separate cadmium and tellurium products.
Here’s a look at how that works:
Solar recycling companies
In Europe, regulations require manufacturers of solar panels to be responsible for the recycling of the products they sell. To make that process run smoothly, PV Cycle was set up as a non-profit membership organization by the solar industry, to help solar manufacturers meet compliance with EU regulations.
PV Cycle has developed a process that enables them to recover 96% of the materials used to make solar panels, with the leftover 4% mostly made up of glass coatings and the EVA encapsulant material, which is sent to a waste-to-energy plant and burned to produce energy.