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| Updated | February 18, 2025 |
What is the Carbon Footprint of Solar Panel Manufacturing?
Carbon Footprint of Solar Panel Production
The carbon footprint of solar panel making is the total GHG emissions at each life cycle stage. It involves raw material extraction, processing, manufacture, transport, installation, and disposal. High energy requirement for polysilicon production is the biggest factor. It uses coal-fired power plants. Moreover, wafering, cell fabrication, and module assembly are energy-intensive processes and require chemicals that emit CO2. Solar panels offset operational emissions. Still, initial energy input, supply chain emissions, and end-of-life disposal impact their carbon footprint.
Factors Contributing to the Carbon Footprint of Solar Panel Production
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Mining and Processing Raw Materials: The carbon footprint of solar panel making includes intensive silicon mining. The necessary temperature for refining silicon from quartz is 1,500-2,000°C. Therefore, the power consumption per kg is very high. Most of the production relies on coal-fired power plants in China, where over 90% of the world's polysilicon is made. Silver, aluminum, and copper production for panel conductivity also generates emissions. E.g., silver mining releases plenty of CO2 per kilogram. And the standard panel has about 6-8 grams of silver.
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Energy Consumption in Manufacturing Processes: Polysilicon purification, wafering, and module assembly use lots of power. Region's energy mix affects wafer production's electricity usage per square meter. Monocrystalline solar panels use more energy than polycrystalline ones because the Czochralski technique melts silicon at above 1,400°C. Deposition of anti-reflective coatings and passivation layers increases energy consumption. In their initial few years, solar panels release 50g of CO2 per kWh.
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Transportation of Solar Panels: Shipping panels worldwide generates emissions. Most solar panels are produced in China. Yet, demand is high in Europe and North America. A container can transport many panels, but shipping one from Shanghai to Los Angeles emits enough CO2. Road and rail transport add emissions. E.g., moving panels from a port to an inland installation site can produce a considerable quantity of CO2 per kilometer per panel. Also, glass and aluminum frames increase weight for higher fuel consumption. The logistics chain is key to the carbon footprint of solar panel deployment.
How Much CO2 Do Solar Panels Release During Their Lifecycle?
Lifecycle CO2 Emissions of Solar Panels
The carbon footprint of solar panels counts in their manufacturing phase. It entails the extraction and processing of polysilicon, glass, and metals. For instance, producing one square meter of PV modules demands huge energy. It prompts emissions from 37.3 to 72.2 g CO2e/kWh when installed in regions with high solar irradiance, depending on the energy mix of manufacturing location and the efficiency of production processes. Additionally, transportation, installation, and maintenance add to the carbon footprint of solar panels. End-of-life disposal and recycling are evolving. Their environmental implications are yet to be quantified.
Comparison: Carbon Footprint of Solar Panels and Fossil Fuels
From coal-fired power plants, the average lifecycle emissions is 820 g CO2e/kWh. Meanwhile, gas combined cycle plants release 490 g CO2e/kWh, and utility-scale solar PV systems only 33-50 g CO2e/kWh. This shows how solar energy reduces greenhouse gas emissions. The carbon footprint of solar panels may decrease as technology and manufacturing improve. Undoubtedly, it heightens their environmental advantage over fossil fuels.
Long-Term Environmental Benefits of Solar Panels
Although they emit carbon during manufacture, solar panels provide long-term environmental perks. PV systems may have an energy payback time (EPBT) of 2-5 years per technology and region. In a few years, a solar panel produces the energy needed for its creation, offsetting its initial carbon footprint. For most of its lifetime, solar panels provide emission-free power. Besides, advancements in recycling technology will reduce end-of-life environmental impacts, further lowering the carbon footprint of solar panels.
How to Reduce the Carbon Footprint of Solar Panel Manufacturing
Innovative Technologies Minimizing Emissions During Production
Use emission-reducing technologies to decrease the carbon footprint of solar panel manufacturing. One of them is the development of silicon heterojunction (SHJ) solar cells. They operate at lower temperatures during production than traditional methods. The reduction in thermal requirements implies decreased energy consumption and, hence, lower greenhouse gas emissions. The EPBT and lifecycle CO2-equivalent emissions per kWh of an SHJ module might also be less than a regular monocrystalline module. Besides, the shift towards lead-free soldering techniques in PV manufacturing eases lead-related environmental hazards. It backs environmental regulations to further lessen the carbon footprint of solar panel production.
Utilizing Renewable Energy Sources in Manufacturing
Renewable energy sources in manufacturing solar panels lower their environmental impact. While powering production facilities with clean energy, manufacturers can diminish the carbon footprint of solar panel manufacturing. A NREL study highlighted that manufacturing with a cleaner energy mix (compared to a coal-rich mix) can decrease emissions by a factor of two.
Recycling and Repurposing Materials to Enhance Sustainability
Repurposing and recycling materials improves solar panel manufacturing sustainability. Recycling programs help recover polysilicon, silver, and glass from decommissioned panels. It disregards virgin resource extraction and environmental degradation. What is more, recycling processes can lower the carbon footprint of solar panel manufacturing with less raw material processing energy consumption. For example, recycling wafers can save energy and produce new wafers. Also, repurposing materials supports circular economy principles, so end-of-life panels create new panels for a sustainable life cycle for PV products.
Additional Note
To further decrease the carbon footprint of solar panels, Infolink recommends manufacturers adopt materials with lower carbon emissions, including Fluidized Bed Reactor (FBR) granular polysilicon, which offers a better carbon profile than traditional polysilicon. In addition, laser-enhanced contact optimization (LECO) should be implemented for cell efficiency to cut emissions per watt. For an analysis of such approaches, please visit our website.