We all know that fossil fuels are the greatest villains in the story of climate change. But the good guys—i.e. renewable energies—can also do great environmental damage. Here’s what you didn’t know about solar panels.
Really? You’re going to ruin solar energy for me?
No, no, there’s absolutely nothing wrong with solar power. It’s really about solar panels—and the fact that we haven’t figured out how to recycle them. But where there are problems, there are solutions.
Let’s start with what these panels are made of—and how they work…
Say hello to photovoltaic cells: These are also called solar cells—because they convert solar energy into electricity. They are made up of semiconductor material—as in they can sorta conduct (semi) electricity, but not as well as, say, metal. When the sun shines on a cell, this material absorbs the light and transfers the energy to electrons—which flow through it as electricity—which can be used to power your home or a grid.
Say hello to the sandwich: A solar panel is like an “electronic sandwich.” The solar cells form the ‘filling’—protected on both sides by sheets of polymer and glass: “It’s all held together in an aluminium frame. On the back of the panel, a junction box contains copper wiring that channels electricity away as it’s being generated.” It looks like this:
A great mountain of panels: We don’t have an exact estimate, but experts say we have installed more than one terawatt of solar capacity: “Ordinary solar panels have a capacity of about 400W, so if you count both rooftops and solar farms, there could be as many as 2.5 billion solar panels." The world consumes 15 terawatts of energy from renewable sources each year.
In India, we have installed a solar capacity of 70.1 gigawatts—and have a target of 280 GW by 2030. (One gigawatt is equal to one billion watts; one terawatt is equivalent to one trillion watts). So that’s a lot of solar panels just in India.
And what’s the recycling problem?
The first problem is of sheer scale. By 2050, 78 million metric tonnes of solar panels will have reached the end of their lifespan—which typically ranges from 25 to 30 years. The global total of solar-panel waste generated per year will rise from 30,000 metric tonnes in 2021 to more than one million tonnes in 2035—and will hit 10 million tonnes by 2050. That’s a lot of electronic waste.
But, but, but: The numbers above are likely an underestimate—according to this 2021 study. The 2050 projections—made by the International Renewable Energy Agency (IRENA)—assumes that customers will hold on to their solar panels for their entire lifetime—i.e. around 30 years. It is far more likely that customers will replace their solar panels much earlier—opting for cheaper and far more efficient models. According to the HBR statistical model, the amount of trash will be 50X higher than the IRENA number of 78 million metric tonnes.
The study’s chart shows a ‘solar trash wave’—which you can see below. The green line assumes there are no failures in the panels—and all customers keep their panels for the entire lifetime. The blue line represents IRENA’s projection—which assumes some wear and tear. The red line represents the estimate of the 2021 model.
As for India: A 2016 IRENA report predicted India will generate more than four million tonnes of solar waste by 2050. A study published in February predicts we will generate 600,000 tonnes by 2030—rising 32X to more than 19 million tonnes by 2050. Five states—Rajasthan, Gujarat, Karnataka, Tamil Nadu, and Andhra Pradesh—will produce 65% of this waste, since they have the largest solar capacity. We will become one of the top five leading generators of solar waste by 2045-2050. Presumably, a model that factors in early replacement will result in a ‘solar trash wave’ of our own.
So why can’t we recycle the panels—like any other kind of e-waste?
Because they need “bespoke” recycling plants. Using standard ones used to recover electronic waste makes zero financial sense:
At a typical e-waste facility, this high-tech sandwich will be treated crudely. Recyclers often take off the panel’s frame and its junction box to recover the aluminium and copper, then shred the rest of the module, including the glass, polymers, and silicon cells, which get coated in a silver electrode and soldered using tin and lead…
As a result, the more precious materials in a panel—like silver and silicon—are not recovered. This in turn reduces the value of the waste:
[A] recycler taking apart a standard, 60-cell silicon panel can get about $3 for the recovered aluminium, copper, and glass… [But] the cost of recycling that panel in the U.S. is anywhere between $12 and $25 — after transportation costs, which “oftentimes equal the cost to recycle.”
The cost far exceeds any potential revenue—by a 10-to-1 ratio.
India’s bigger problem: is the lack of recycling. Only 20% of the waste is recovered:
As a result, the waste often accumulates at landfills. Landfill disposal in turn causes acidification, leaching of toxic metals (such as lead and cadmium) into the soil, and contaminates the local water. Gradual incineration of the panel encapsulant also releases sulphur dioxide, hydrogen fluoride, and hydrogen cyanide into the atmosphere.
Again, a lot of this has to do with the lack of any financial incentive to recycle. India doesn’t have a market for recycled solar waste:
“Most solar plants are located in remote areas, so the logistics and transportation is expensive, and once dismantled there is hardly any money from each individual part,” says Srinivas Vedula from EPragathi, a Bengaluru-based e-waste recycling company. “Plus, the solar glass has no value.”
[Atif] Mirza, who is the official contractor for Ayana Renewable Power’s plants across India’s solar parks, including in Pavagada, says he sells dismantled parts to traders but admits: “We don’t know what they do with it.”
As with all else in India, the government has framed strict regulations—which are rarely enforced.
The real solar kachra industry: Most of the junked panels end up in the hands of poor rubbish collectors—who dismantle them by hand. They have learned to scrape out the silver and other precious material—safety be damned.
So how do we fix this?
Let’s start with the good news. Solar waste can potentially be very valuable because of the materials it contains. For example, the 340,000 tonnes of waste we will generate each year by 2030 will be made up of 10,000 tonnes of silicon, 12-18 tonnes of silver, and 16 tonnes of cadmium and tellurium. According to IRENA, materials recovered from solar waste around the world could be worth $450 million by 2030 and $15 billion by 2050. So there is plenty of reason to get better at extracting value—literally—from a solar panel.
Panning for silver & more: A first-of-its-kind solar waste recycling plant in France has figured out how to extract and re-use 99% of a panel’s components. The most valuable components of a solar panel are silver, silicon and copper—and they are the hardest to extract and/or purify:
Each solar panel contains only tiny fragments of these precious materials and those fragments are so intertwined with other components that, until now, it has not been economically viable to separate them. But because they are so valuable, extracting those precious materials efficiently could be a game-changer, says [CEO of Soren—a waste management company—Nicolas] Defrenne. "Over 60% of the value is contained in 3% of the weight of the solar panels," he says.
Recycle & reuse: US-based First Solar Inc. recycles its own solar panels—and recovers close to 95% of the materials. These are used in a variety of products—“such as the semiconductor for new panels, glass for bottles and laminate for rubber mats and bicycle handles.” Interestingly, First Solar is also moving away from using silicon as a semiconductor in its panels:
First Solar’s thin-film panels use a compound called cadmium telluride in the semiconductor instead, which the company says it can recover and reuse. It says its cadmium telluride semiconductor can be reused up to 40 times.
Also this: The European Commission is funding a range of projects that demo how solar panels can be repurposed for a range of innovative uses—from powering e-bike charging stations in Berlin to housing complexes in Belgium.
Point to note: US sellers are already hawking second-hand panels on to less affluent countries—to get rid of their e-waste problem: “And those countries typically don’t have regulations for electronics waste. So eventually, you’re dumping your problem on a poor country.”
The bottomline: Srinivas—the Bangalore e-waste entrepreneur—says: “The government policy on solar waste is: let’s cross the bridge when we come to it.” Unfortunately, the bridge is already here. We’re just refusing to see it.
Reading list
The Grist and Wall Street Journal (paywall) look at the big picture on solar waste—and possible solutions. BBC News has more on new approaches to recycling. Harvard Business Review has more on the statistical model predicting a solar trash wave. The Hindu and The Guardian are best on solar waste in India—while Indian Express has more on the latest study on solar waste. The New York Times has an adjacent article on the effect of renewable energy industries on wildlife. The Print looks at the human costs of renewable energies. Inside Climate View offers a counter-argument—dismissing overblown concerns about the impact of solar waste.
