How Much Waste Does Solar Power Produce?
Solar power has emerged as an increasingly important renewable energy source. The ability to harness energy directly from the sun offers significant environmental benefits compared to fossil fuels. However, there are concerns regarding the potential environmental impacts from solar power, including waste generated during manufacturing, installation, operations, and decommissioning of solar panels. With solar capacity expanding rapidly, there is growing interest in understanding and minimizing any negative environmental effects.
Solar Panel Materials
Solar panels are primarily made of silicon, a semiconductor material that allows solar cells to absorb sunlight and convert it into electricity through the photovoltaic effect. The most common types of silicon solar cells are monocrystalline silicon and polycrystalline silicon. Monocrystalline silicon is made from a single cylindrical crystal of silicon, while polycrystalline silicon is made from multiple silicon crystals melted together. Both have advantages and disadvantages in terms of efficiency and cost.
Other semiconductor materials used in solar panels include cadmium telluride, copper indium gallium selenide (CIGS), and amorphous silicon. Cadmium telluride and CIGS solar cells are examples of thin-film solar cells, which use very thin layers of photovoltaic material and are lighter and more flexible than traditional silicon cells. Amorphous silicon is a non-crystalline form of silicon with lower efficiency but easier manufacturing.
In addition to the photovoltaic semiconductor material, solar panels are composed of a top layer of glass to allow light to pass through while protecting the semiconductor material. They also contain an encapsulant material like ethylene vinyl acetate to seal and adhere the solar cell layers together, as well as a bottom backing layer of material like aluminum or plastic for structural support.[1]
Wires and electrical connections are also part of a solar panel’s structure to conduct electricity from the solar cells out of the panel. The frame and casing surrounding the panel are typically made of aluminum, enabling panels to be mounted and secured.[2]
Sources:
[1] https://www.azom.com/article.aspx?ArticleID=21383
[2] https://www.energysage.com/solar/what-are-solar-panels-made-of-list-of-solar-pv-materials/
Manufacturing Waste
The manufacturing of solar photovoltaic panels produces some waste and emissions. While solar power is much cleaner than fossil fuels overall, producing solar panels does have some environmental impacts.
The main waste from solar panel production comes from the energy-intensive processes involved in purifying silicon and other semiconductor materials. This generates greenhouse gas emissions, as well as air pollutants and liquid waste. However, most emissions occur during the initial energy-intensive purification and ingot-casting processes. Once purified silicon wafers are produced, the rest of the manufacturing process is much cleaner.1
There are technologies available to recycle up to 80% of process chemical waste back into production, greatly reducing the amount of waste.2 Some solar panel manufacturers are also implementing closed-loop water cooling systems to minimize water usage and discharge. Overall, steady improvements in solar cell efficiency means less semiconductor material is required per watt of solar power produced.
While recycling has improved, there are still challenges in recycling all solar panel manufacturing waste sustainably. The industry is investing in new recycling technologies to further minimize environmental impacts.3
Installation Waste
Installing solar panels produces some amount of waste from the transportation and installation process. Panels and mounting equipment like rails and racks need to be shipped to the installation site, which generates greenhouse gas emissions from fuel consumption. According to one analysis, transporting ground-mounted solar panels emits approximately 30 grams of carbon dioxide per kilowatt-hour of electricity produced over the system’s lifetime (https://magnoelia.com/).
There is also some waste generated during the installation process itself. Panels may need to be trimmed or modified to fit on particular roofs or sites, which can create scrap material. Installers use tools, equipment, packaging and other materials that produce waste. Proper disposal of any toxic metals or electronics that get damaged during installation is important as well.
Overall the installation process generates substantially less waste than the manufacturing stage. Using local or regional installers when possible reduces transportation miles and emissions. Proper planning to minimize on-site cuts and waste helps reduce scrap. Responsible installers will recycle materials, reuse components when feasible, and safely dispose of any hazardous installation waste.
Operational Waste
Operational waste from solar panels during their working lifetime is minimal. Solar panels produce electricity through photovoltaic cells that convert sunlight into direct current electricity. This process does not generate any waste or byproducts.
While operational, solar panels may require periodic cleaning to remove dust, dirt or snow that can accumulate on the panels and reduce efficiency. The cleaning solutions used are typically water or other mild cleaners that don’t contain toxic chemicals. Proper solar panel maintenance and cleaning techniques minimize the potential for any hazardous runoff.
One study found extremely low levels of lead and cadmium leaching from broken solar panels in a laboratory test designed to simulateworst-case weathering scenarios, but noted leaching would likely be orders of magnitude lower under normal operating conditions (Solar Panels: Decommissioning & Recycling). So leaching of hazardous materials from intact, operational solar panels is generally not a significant concern.
Overall, compared to the waste streams from fossil fuel energy sources, the operational phase of solar photovoltaics generates very little waste. With proper solar panel maintenance, operational waste is negligible.
Decommissioning Waste
When solar panels reach the end of their usable lifespan, typically around 25-30 years, they must be properly decommissioned and disposed. Decommissioning waste is created when panels are uninstalled and collected for recycling or disposal. According to ERI, a leading solar panel recycler, solar panel recycling requires careful handling of the different components like aluminum, glass, polymers, and semiconductors [1].
Proper solar panel disposal is important to minimize waste and environmental impact. Solar panels contain lead and other toxic materials that can leach into the environment if landfilled. Recycling recovers about 80% of solar panel materials for reuse [2]. The semiconductor material is lost in recycling, but new methods aim to improve recovery rates.
The cost of responsible solar panel disposal and recycling ranges from $20-30 per panel [3]. Some states like California now require solar companies to collect a deposit and have a recycling plan in place. Overall, experts emphasize the importance of proper planning for solar panel end-of-life management to minimize waste.
Toxicity
There have been some concerns raised about the toxicity of materials used in solar panels. Some of the key materials that have drawn attention include:
- Silicon tetrachloride – a byproduct from producing solar grade silicon that is hazardous if released into the environment (Source)
- Cadmium telluride – a thin film material that is toxic and carcinogenic, but makes up a very small amount of the total solar panel (Source)
- Lead – found in solder and wiring in some solar panels (Source)
However, it’s important to note that solar panels contain small amounts of these toxic materials sealed within the panels. The amounts used are regulated and not considered dangerous if the panels remain intact throughout their life cycle. Proper recycling and disposal of solar panels is important to prevent any potential leakage of toxic materials. In comparison to other energy sources like coal and nuclear, the toxicity risk from solar power remains relatively low. Many companies are also exploring less toxic and more sustainable alternatives for solar manufacturing.
Comparison to Other Energy Sources
When compared to fossil fuels and nuclear energy, solar power produces significantly less toxic waste over the lifetime of a solar farm. Fossil fuels like coal and natural gas produce massive amounts of air pollution and carbon emissions when burned to generate electricity. According to a 2023 study by Our World In Data, fossil fuels are the dirtiest and most dangerous energy sources due to their emissions and environmental impact (Ritchie).
Nuclear energy, while producing zero emissions, generates radioactive nuclear waste that requires secure long-term storage. Per unit of energy produced, nuclear energy produces around 300 times less waste than solar panels according to Environmental Progress (Mackinac Center). However, the radioactivity and toxicity of nuclear waste poses unique challenges. Overall, solar power’s relatively minimal waste compared to fossil fuels and manageable waste compared to nuclear makes it one of the cleaner energy sources available today.
Waste Minimization Efforts
There are several efforts underway to try to reduce the amount of waste produced by solar panels over their lifecycle. Some key strategies include:
Enhancing panel efficiency – By improving the efficiency of solar panels, manufacturers can produce the same amount of electricity with fewer overall panels, reducing material inputs and future waste (https://de.tw-solar.com/news/96.html). Companies like REC Group are focused on innovating to create more efficient panels.
Recycling programs – Creating recycling systems to recover materials from decommissioned solar panels can reduce the amount sent to landfills. Programs exist in Europe, Japan, and some U.S. states to recycle solar panel components.
Design for disassembly – Manufacturing panels so they can be more easily taken apart at end-of-life allows materials to be more readily recovered and recycled.
Takeback programs – Some solar companies are beginning to offer panel takeback and recycling services to customers to ensure proper end-of-life handling.
Reducing material inputs – Using thinner silicon wafers, alternative metals to silver, and minimized framing/ casing can reduce waste.
There is still more work to be done to optimize solar manufacturing and recycling to minimize lifecycle waste. But solar companies, researchers, and regulators are increasingly prioritizing strategies to reduce the environmental impacts of these clean energy technologies.
Conclusion
Solar power produces limited waste compared to other energy sources like fossil fuels. The main waste streams stem from manufacturing and end-of-life panel disposal, but toxicity is low and proper recycling processes help minimize waste accumulation in landfills.
While solar panel production creates some waste from mining, refining, and assembly, operational waste is negligible. And the panels at end of life can be recycled to recover 80-90% of their materials for new products. Compared to fossil fuels that constantly produce emissions and toxic byproducts, the small amount of solar waste is promising.
Considering the lifespan of a solar panel is around 25-30 years, the waste generated per kWh produced is far below coal or natural gas plants. As solar continues to scale up and recycling processes improve, the waste impact should only diminish further. Overall, solar power remains one of the lowest waste and cleanest energy sources available today.
