I often hear people say, “The sun is a free resource; once the solar panels are installed, you have an infinite supply of energy.” True! I completely agree. But. There’s always a “but.” To actually install those solar panels, you need other resources that are materials, that depend on supply chains, that can become scarce, and that are subject to geopolitical challenges.

I’ve been researching the material aspects of the energy transition for some time now, and here I’ll use silver as an example. We’re used to thinking of silver as a precious metal for jewelry, cutlery, and photography. But over the past decade, it has quietly become an indispensable structural element for the development of clean energy.

Every silicon solar cell uses silver paste to form the electrical contacts that collect electrons from sunlight. The combination of conductivity, corrosion resistance, and long-term stability that silver offers is truly difficult to replicate. So, although manufacturers have worked hard to reduce the amount of silver per watt... and have done so impressively (!), dropping from about 65 mg/W to less than 20 mg/W, solar energy continues to grow faster than these technological improvements. According to the Silver Institute, the photovoltaic industry used approximately 200 million ounces of silver in 2024, and this already represents about a quarter of all silver mined globally that year.

Some studies actually reveal that if a net-zero policy is followed, solar panel production could reach a silver demand in 2040 equal to silver production. I am certain that new technologies will be introduced, but that does not mean we should be blind to the facts.

Moving beyond solar panels, I’d like to mention electric cars. Although the amount of silver used in each is truly minimal (25–50 grams of silver per vehicle, compared to 15–28 grams in a combustion-engine car), the 17 million electric vehicles sold in 2024 translate those grams into hundreds of tons of silver (IEA data).

The other side of the coin is the supply of silver. It is well known that silver is primarily a byproduct extracted from lead, zinc, and copper mines. There are very few “silver mines,” so silver production cannot simply be increased just because demand is growing. Keep in mind that the market has been in deficit for three consecutive years.

This doesn’t mean that the energy transition is condemned to failure or that solar energy is a bad idea. But I do want to highlight something worth keeping in mind: electrification doesn’t eliminate our dependence on resources; it simply restructures it. The pressure basicalyl goes from fuels to metals, from oil fields to mining supply chains. And silver is just one example: copper, rare earths, cobalt(!), lithium... all of them play a role in the electrification that we should be aware of. And in this analysis, I wasn't focusing on the demand for future AI centers; honestly, I'm curious to see what the supply of silver will look like in a few years.

If you’d like to see the full analysis and refs, just take a look at raw-science.org (in spanish)