Some people may mistake solar technology as magic, sorcery, or from another planet, but solar panels and solar batteries are just made up of minerals found right here on earth. As one of the most prominent forms of energy being developed to reduce global carbon emissions, the increased popularity of clean energy has created a high demand for all of the raw materials used to create solar panels, batteries, and other renewable energy system components.
So while it's true that supporting a clean energy transition has many long-term environmental benefits, going solar can only achieve a net positive impact on the planet if the minerals used in the technology are sourced and processed sustainably. To illustrate the environmental effects of photovoltaic (PV) solar panels, let’s take a look at the many critical minerals used in the solar industry, as well as how they are mined, refined, and used to generate renewable energy.
The Minerals In Solar Panels
While solar panels use the nearly infinite power of the sun to create renewable energy, a variety of non-renewable minerals that are mined from the earth make up the physical components of these green power systems. In the 2020s, most solar panels contain a combination of the following minerals:
- Aluminum
- Cadmium
- Copper
- Gallium
- Indium
- Lead
- Molybdenum
- Nickel
- Silicon
- Silver
- Selenium
- Tellurium
- Tin
- Zinc
It’s a long list of materials, including some rare earth elements, but some of these minerals are only currently used in laboratories, within thin-film solar panels, or as a part of various emerging solar technologies. For this article (and so we don’t overwhelm you), we will focus primarily on the minerals used in the solar panels often installed on residential roofs.
Where Are the Minerals in Solar Panels Found?
For both solar panels and solar storage, some of the minerals used in production are found in specific locations, whereas others are found in large quantities across the planet.
Aluminum
The most abundant metallic element in the earth’s crust, aluminum can be found in igneous rocks (solidified from lava or magma) across the planet in the form of bauxite ore. Ore is natural rock or sediment that contains one or more valuable minerals and metals. The leading aluminum mines are located in Australia, Brazil, Guinea, Jamaica, and Vietnam.
Copper
Copper is a significant ingredient in the global transition to lowering our carbon emissions, as its high conductivity is essential for electricity generation. Chile is the world's leading producer of copper, followed by Peru, China, DR Congo, and the United States.
Silicon
Silicon is the second most abundant element in the earth's crust, after oxygen. The leading silicon miners worldwide include China, Russia, the United States, and Norway.
Silver
Silver is found in electrum alloy, a naturally occurring alloy of gold and silver, with trace amounts of lead, copper, and zinc. As a result, most of the silver used in today's manufacturing industry is obtained when processing other ores. Mexico has the largest annual silver production, and other leading silver producers include Peru, Poland, Norway, Canada, the U.S., and Bolivia.
Zinc
Zinc is found in over 50 countries globally, with the leading producers being Canada, Australia, China, Peru, and the U.S. Currently, Alaska’s Red Dog Mine is the largest zinc mine in the world.
Beyond these “big 5” minerals, there are also some rare earth minerals in solar panels that are found in various parts of the world:
- Selenium: Although selenium-rich ores exist, the selenium used in solar panel manufacturing is usually obtained as a copper byproduct. The element is primarily mined in Japan, Canada, Belgium, and the United States.
- Gallium: While gallium isn’t present as a free element in the earth's crust, miners extract it from other minerals such as aluminum, zinc, bauxite, sphalerite, coal, and germanite.
- Nickel: One of the essential metals in our everyday lives, nickel is found in the largest quantities in Indonesia, followed by the Philippines, Russia, Canada, Australia, and Brazil.
- Indium: A sulfide substitute in base minerals such as stannite, sphalerite, chalcopyrite, and stannite, indium rarely occurs geologically, so miners recover it from lead and zinc byproducts. China is the leading indium producer, followed by South Korea, Japan, and Canada.
- Tellurium: Obtained as a copper processing byproduct, tellurium is mainly mined in Japan and China.
How the Minerals in Solar Panels are Mined and Refined
As global solar capacity continues to increase, proper resource management is important for the industry to maintain sustainability. For long-term success, miners and manufacturing plants will need to appropriately manage their source materials to avoid adverse environmental impacts.
Aluminum
Using a surface-based method called open-cut mining, aluminum is sourced from the earth principally as bauxite ore. Once dug up, the ore is then crushed, dried, and cleaned before being sent out for shipping and processing.
Bauxite ore becomes aluminum using the four-part Beyer refining process: digestion, clarification, precipitation, and calcination. Here, the bauxite is refined into its alumina form and then smelted to create aluminum.
Copper
Copper is mined from open pits and crushed during extraction and production. The open-pit process involves digging stepped benches into the earth, using a boring machine to drill holes, and then detonating explosives within them.
After mining, the copper ore is processed by grinding it roughly to separate any waste material. The copper is then hauled to a plant or smelter for refining. Copper refining removes impurities, leaving the refiner with 99.9% pure copper, the highest grade of copper.
Silicon
Silica is another name for industrial sand and gravel that has a high silicon dioxide (SiO2) content and can be refined into silicon. Silica mining uses open pits or dredging with standard mining equipment. Apart from the temporary disturbance in the immediate area, the silicon mining process has a minimal environmental impact on surrounding areas.
Silica metal is made of silica dioxide and carbon materials, so its refining process aims at separating the minerals from their surrounding impurities. When the raw materials are placed in a furnace that’s heated to 4,000° F, melting allows the materials to form into solid silicon and carbon monoxide.
Refiners then treat the metal with oxygen while it is still in the molten state, removing calcium and aluminum impurities. After this process, the resulting product is 98.5%-99.9% pure silicon (with minimal traces of aluminum and calcium) and poured into pots for cooling.
Silver
About 80% of the world's silver is produced as a byproduct of other minerals such as gold, lead, zinc, copper, and uranium. The remaining percentage comes from mining activities using open-pit methods in which heavy machinery reaches mineral deposits near the earth's surface.
After extraction, silver ores are crushed, ground down, and then separated through floatation to achieve 30-40 times the mineral concentration than its naturally occurring state. Refiners then put the extracted silver through electrolysis (a technique that uses direct electric current to create a chemical reaction) to concentrate it further.
Zinc
Zinc is mined underground using various techniques that include creating a near-horizontal passageway in a mine (called a “drift”) along a vein of zinc. Miners use a drill to blast a drift, so they can remove the zinc ore before hoisting it on the surface for concentration. After mining, the zinc ore is roasted to remove sulfur impurities and then processed using electrolysis.
How Are Minerals Used in Solar Panels?
The primary minerals used to build solar panels are mined and processed to enhance the electrical conductivity and generation efficiency of new solar energy systems.
- Aluminum: Predominantly used as the casing for solar cells, aluminum creates the framework for most modern solar panels. It’s the perfect metal for the frame because it’s lightweight, conducts heat, is durable, and can be easily recycled for other uses.
- Copper: Thanks to high conductivity and durability, copper is essential in solar manufacturing to increase the efficiency and performance of solar panels.
- Silicon: Silicon is the primary mineral that solar panels use to generate electricity. With crystalline semiconductivity and light-absorbing properties, silicon captures and converts sunlight into the free electrons that are used to create electricity within solar cells.
- Silver: Turned into a paste by solar manufacturers and loaded onto each silicon wafer, silver is primarily responsible for carrying new solar electricity from the panels to the point of use, or the battery storage system.
- Zinc: Used in solar panels to improve energy conversion, zinc continues to be utilized in high-tech solar generation because of its enhanced efficiency.
Negative Environmental Impact of the Minerals in Solar Panels
Unfortunately, if the minerals used to create solar power systems are handled or used incorrectly, this can create a variety of negative environmental implications:
- Aluminum: When present in high concentrations, aluminum can be very toxic to freshwater aquatic animals. Easily recycled, over 75% of the aluminum that has ever been produced is still in use today. However, the actual mining and refining processes are very resource-intensive.
- Copper: If released into the environment during mining, copper attaches to organic matter, clay, soil, and sand. This causes its compounds to release free minerals into local water, air, and food, which can harm aquatic and land-based life, reducing survival, reproduction, and growth.
- Silicon: During mining, silica particles may accumulate on the leaves of nearby plants, interfering with photosynthesis and the respiration process.
- Silver: When silver is produced in large quantities, mercury emissions may be released into the water, air, and soil, resulting in local human health concerns and environmental damages.
- Zinc: If large amounts of zinc are released into the environment during processing, it can affect water resources, crops, soils, and vegetables. In locations with heavy pollution, this can cause a variety of negative effects on human health.
The Minerals in Solar Batteries
While new technologies are constantly being explored, the majority of today’s solar batteries are made of one of three different compound compositions:
- Lead-acid
- Lithium-ion
- Saltwater
As the predominant technology used in new residential solar batteries, it is important to know that lithium-ion batteries often contain a range of elements and minerals beyond their “lithium” namesake. This includes:
- Chromium
- Cobalt
- Graphite
- Manganese
- Vanadium
Where Are The Minerals in Solar Batteries Found?
Lead
Lead reserves are found in many different countries across the world. China is the leading producer, followed by Australia, Peru, the United States, Mexico, and Russia.
Lithium
Lithium is the 33rd most abundant element in nature. Today, Chile has the largest lithium reserves globally, followed by Australia, Argentina, and China.
How Are the Minerals in Solar Batteries Mined and Refined?
Lead
The solar manufacturing industry utilizes both newly mined and recycled lead resources. Lead mining involves extracting ores from points underground by using highly mechanized methods, or open pits.
After extraction, lead is ground into fine particles, similar to table salt texture. It's then put through a floatation process by mixing it with water, pine oil, and air bubbles to form an oil froth. The lead ore floats on the froth, and the foam is skimmed and filtered to remove the water. Then, the powder is heated at over 2,500°F to remove impurities before being converted into molten lead.
Lithium
A highly reactive alkali metal, lithium is found in underground clay deposits, brine, mineral ore, geothermal water, and seawater. Miners begin by drilling a hole, which they use to pump brine to the surface. Once on the surface, the brine is left alone for months to allow evaporation to remove the water.
The remaining lithium is then filtered and placed into another evaporation pool. This long process can take anywhere between eight months to three years to obtain usable lithium.
How Are Minerals Used in Solar Batteries?
To help you understand modern storage options, let’s take a more detailed look at the three main solar energy storage systems that are currently being used in residential applications, and their primary solar battery materials:
- Lead-Acid: Lead-acid batteries contain a mixture of sulfuric acid and water (electrolyte), a lead metal plate with a negative charge (anode), and a positively charged lead dioxide metal plate (cathode). The plates are suspended in the electrolyte to store electricity.
- Lithium-Ion: The most common option for storing excess solar energy, lithium-ion batteries require less maintenance, last longer, are more efficient, and have higher energy density than lead-acid batteries. That’s why you also see lithium-ion batteries powering electric vehicles as well as powering homes.
- Saltwater: Saltwater battery systems replace lithium with sodium, the element found in table salt, resulting in a saltwater solution that can capture, store, and discharge energy. As a result, saltwater batteries are recyclable and maintain a long lifecycle, but may not have the same energy storage capacity.
Environmental Impact of the Minerals in Solar Batteries
Both the lead and lithium used to create solar battery storage can be problematic if released into the environment without proper care.
Lead: Whether released during mining or by disposing of a battery improperly, lead-acid particles can leak into the soil, air, and water. Over time, this can cause considerable pollution.
Lithium: During lithium mining, toxic chemicals may be released into nearby bodies of water, contaminating and causing harm to both aquatic life and animals that drink from that source.
Environmental Impact of the Minerals in Solar Panels and Solar Batteries
Learning more about solar panel production is the first step in understanding the environmental benefits of going solar, and the steps the industry is taking to reduce any potential environmental concerns. When we recognize how the minerals used in solar technology are mined and refined, we have a better chance of creating even more sustainable solutions to help combat global warming.
While solar power is certainly a renewable energy resource, this does not mean that all of the minerals used to create the technology are guaranteed to have an eco-friendly profile. To minimize the economic impact of newly mined and processed materials, the solar industry must follow necessary precautions in minimizing soil disturbance, controlling gas emissions, implementing soil and water treatments, and preventing acid rock drainage.
If we’re going to truly create a better world with sustainable energy systems, the solar industry must continue to evolve its supply chain. While panels can generate emission-free electricity, the world should keep a close eye on the various materials and processes that can be used in manufacturing and development, to continue making these processes more eco-friendly.
If you want to learn more about installing solar panels on your home, talk to the experienced solar professionals at Palmetto today. You can start by using our Free Solar Design and Savings Estimate Tool to see a mock-up of how solar panels might look on your roof, and what you could save by going solar.
