The richest silver mine isn’t underground: It’s in solar panels

Silver has become one of the most important materials in the clean energy transition. It’s essential for solar photovoltaics, and solar is no longer a minor consumer of silver. It’s becoming one of the largest drivers of demand—at the same time that ore grades are declining and supply is getting harder to expand quickly.

In other words, even as solar gets cheaper and more efficient, its material foundation is tightening.

This is not just an academic concern. Silver price reached an all-time high this month ($95 per troy ounce), and policymakers are signaling urgency. The U.S. recently included silver in its list of critical materials—an indicator that this metal is increasingly being treated not as a commodity, but as strategic infrastructure.

I’ve been working in e-waste and solar panel recycling for over a decade. The conclusion has only strengthened with time: recycling is not simply a sustainability add-on. It is becoming an industrial requirement.

When solar panels start to look like silver reserves

Ten years ago, my colleagues and I published what is still to date my most cited paper. We characterized silicon solar panels, quantified silver content in the PV, and evaluated pathways to extract it. We measured silver concentrations comparable to a high-grade mine—except here, it’s embedded in a manufactured product that’s already been deployed at global scale. Even a decade ago, solar panels were comparable to primary ore as a source of silver if you evaluate the problem through the lens that matters most to supply: concentration, recoverability, and scale. But since that paper was published, a lot has changed, including what’s underground.

The long decline of ore grades (and why it won’t reverse)

There’s a pattern in natural resource extraction that’s as old as mining itself: we start with the easiest material to extract, burning through the best deposits first. Silver ore grades have been declining for years––researchers reported a 35% decrease between 2007 and 2016. Taking the ore grade from the Fresnillo mine (Mexico) as a proxy for recent years (2015-2024), alongside industry reports on producers’ yields, the trend shows a sustained decline and grades currently at 150-160ppm! In other words, there are 150 to 160 grams of silver for every metric ton of rocks, which is roughly the weight of a chocolate bar dispersed through the weight of a small car.

That creates an uncomfortable reality: if society continues to depend on primary mining alone to meet future silver demand, the silver we get will increasingly come from more energy-intensive, more environmentally disruptive extraction.

Silver demand is rising, learning curves are taming it

Silver isn’t “just a solar material.” It’s a critical input for multiple industries that underpin modern life: electronics, electrical contacts, industrial manufacturing, medical applications, and more. Solar is simply the newest massive demand center—and one of the fastest growing.

And because solar deployment has become a central strategy for decarbonizing electricity globally, silver demand is now tethered to something bigger than price curves or market hype. It’s tied to the reality of the energy transition.

More recently, my colleagues and I published another paper analyzing what I consider one of the most revealing metrics in the entire solar supply chain: the silver learning curve, the amount of silver required to produce a watt of solar energy and its change over time. Solar has a long history of improving efficiency and reducing material intensity. The industry has been working hard to deliver more watts with less silver per unit of output.

That’s the good news, and it’s real. But the learning curve doesn’t exist in a vacuum. It runs headfirst into deployment volume. Using the silver learning curve and solar growth trends, we estimated that under business-as-usual cell technology (p-type, at the time), the solar industry could consume anywhere from 85% to 98% of global silver reserves by the middle of this century.

That is not a marginal planning issue. That is a constraint with the potential to reshape solar economics, technology roadmaps, and the competitive pressure between industries that all depend on the same metal. And we aren’t just looking at a theoretical future. We can see the trajectory taking shape in the real world as the solar industry’s silver consumption has increased over time. In some reports, solar accounted for ~17% of global silver demand in 2024 and 29% of the total industrial demand. That’s an extraordinary number for a single industrial use case—and it is exactly why silver is no longer a “background material” in the solar story. It’s becoming a determining variable.

Technology shifts can reduce silver per watt—and still spike total silver use

There’s another layer that makes the silver problem more complex than it looks from the outside. Yes, there is a clear trend toward using less silver per watt over time. But solar is not static technology. The industry evolves. And when it evolves, it doesn’t always evolve in a straight line.

When manufacturers make a leap in cell architecture—moving into technologies such as TOPCon or silicon heterojunction—silver use can spike, even if only temporarily. Then the industry works the spike down through process improvement, manufacturing learning, and material optimization. From a distance, it can look like the industry is always “reducing silver.” From inside the data, it looks more like this: downward trend, then a technology jump, then a spike, then a gradual decline again. The impact matters because the transition pathway itself can create periods where the industry becomes even more silver-hungry—exactly when solar deployment is also accelerating. This is how constraints emerge inside success stories.

To be clear, the industry is not ignoring this problem. Manufacturers have steadily reduced silver intensity over time, and newer approaches—such as further metallization optimization and copper-based alternatives—could reduce dependence on silver in the long run. But transitions in solar manufacturing don’t happen overnight. Bankability, reliability, and scale matter, and technology shifts can temporarily increase silver demand before process learning brings it back down. Meanwhile, deployment continues accelerating. That mismatch—fast growth now, material substitution later—is where constraints take hold.

New paradigm: solar panels can contain richer silver than silver ores

Here is the part that still catches people off guard: Modern solar panels often contain silver at concentrations comparable to—or higher than—many mined silver ores. Today’s modules typically fall in the range of roughly 300–400 ppm silver, and that has been the average range for the last several years. We are deploying silver into the field at enormous scale, embedded inside products that have a known service life, predictable retirement windows, and increasingly standardized formats. That is not waste. That is inventory.

It gets even more striking when you treat panels the way any serious metallurgist treats ore: you concentrate the valuable fraction. Solar panels are systems made with different components. The silver is in the cell layer, while other components like glass, aluminum frames, junction boxes are not. The latter components dominate the mass fraction, so when recycling processes remove and separate those non-cell materials, the remaining fraction becomes dramatically more concentrated. In advanced recycling streams, that concentrated material can exceed 1,000 ppm and, in some cases, reach over 2,000 ppm. At that point, “recycling” starts to look less like waste management and more like metallurgy.

Two pathways to the same metal

We now face a choice between two pathways to the same metal. One is primary mining: blasting rock, moving earth at massive scale, and processing increasingly lower-grade material, typically with high energy use and significant environmental impact. The other is an above-ground resource we’ve already manufactured and deployed: solar panels in the field. Those panels are effectively temporary storage for critical materials. When they retire, they either become landfill or feedstock. The difference between those outcomes is not theoretical. It’s infrastructure. It’s decision-making of leaders in the renewable energy space.

Where recycling fits in: from end-of-life service to industrial infrastructure

This is where the solar recycling industry has to evolve. Recycling cannot remain a small, fragmented end-of-life service that only becomes visible when a project is repowered or a warehouse fills up with damaged modules. It has to become industrial infrastructure—built for consistent throughput, high recovery yields, and reliable output streams that downstream manufacturers can actually use. If silver becomes a binding constraint, then recovering silver from end-of-life solar is not just environmentally preferable, it’s one of the clearest ways to reduce pressure on primary supply while keeping the energy transition buildout realistic.

Silver isn’t running out tomorrow but constraints don’t wait for depletion. The point here is not to claim that silver will disappear. Constraints don’t need depletion to become disruptive. They emerge through price volatility, supply friction, and competition between industries that all depend on the same metal. Solar has already proven it can deliver cheaper electricity year after year. The next challenge is whether its material supply chain can scale with the same confidence. The irony is that one of the most concentrated silver resources available to the solar industry may not be underground at all. But already deployed in the field instead.

Dr. Pablo Ribeiro Dias is Co-Founder and Chief Technology Officer at SOLARCYCLE, an advanced solar recycling company and circularity platform producing sustainable and domestic materials at scale. He is a world-renowned researcher in solar PV module and e-waste recycling, conducting leading-edge research in innovative processes and methodologies for high-value, low-cost PV recycling. He has authored numerous influential papers and holds multiple patents in the field.

The views and opinions expressed in this article are the author’s own, and do not necessarily reflect those held by pv magazine.

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