Solar Panels 3x More Carbon Intensive: Renewable Energy Implications

08-08-2023 | By Robin Mitchell

Solar panels are supposed to be the future of green energy, and yet, a new report has highlighted that the carbon impact from solar panels could be three times higher than previously thought. What makes silicon panels so carbon intensive, what does the new report show, and what does this mean for solar panels in the future?

Male technicians are installing photovoltaic solar modules on the roof of a house. Builders wearing helmets are setting up a solar panel system outside, representing the concept of alternative and renewable energy.

New Reports Show Solar Panels Three Times More Carbon Intensive

Over the past few decades, a growing movement of people concerned with the state of the climate has repeatedly pushed to phase out fossil fuels in favour of environmentally-friendly energy sources such as wind and solar. Unfortunately, the holy grain of renewable sources, fusion, is still 20 years away, meaning that the world has had to cope with wind and solar as the primary means of renewable energy.

In the UK, wind energy has proven its worth thanks to the constant prevailing winds inland and strong winds out at sea. In fact, wind energy has proven to be so abundant in the UK that there have been times when wind energy alone made up for the majority of energy generated.

Solar energy, on the other hand, has been demonstrated to be a viable energy source for sunnier locations, typically those closer to the equator, but that doesn’t mean that they don’t work in climates near the poles. For example, solar panels in the UK can actually get a good boost in performance during partially cloudy days when direct sunlight hits the panel and reflected light off clouds also strikes panels. Furthermore, cooler UK temperatures also help increase energy efficiency, making solar panels particularly useful on south-facing roofs.

And yet, for all of the advantages that solar panels are introducing as a renewable energy source, a new report has shed light on the carbon impact of solar panels. According to a new report published by Public (in collaboration with Environmental Progress and The Blind Spot), the world’s biggest manufacturer of solar panels is China, accounting for around 80% of the world’s supply of solar-grade polysilicon and over 97% of the world’s solar wafers. Despite this massive market share, Ecoinvent, which maintains data surrounding carbon emissions from renewable sources, has no data from any Chinese manufacturers. 

The net result of this lack of data is that the true carbon emission levels from solar energy could be as much as three times as previously thought. Considering that solar panels have been previously estimated to produce 12 times less CO2 than natural gas, this figure would shrink this gap significantly. It is also likely that additional recycling steps for solar panels combined with transportation could reduce this gap even further, making natural gas far cleaner than originally thought.

What makes solar panels so carbon-intensive?

The primary reason why solar panels are so carbon-intensive comes down to the use of silicon. 

Polysilicon electricity consumption by region and electricity price 2021

In order to make solar panels, silicon ingots have to be melted down to an extremely high temperature (usually around 1000˚C), and achieving such temperatures requires huge amounts of energy. Once melted, silicon can require the addition of carbon to pull out any oxygen bound to silicon atoms (this directly produces CO2 in large quantities).

For polycrystalline solar panels, this silicon can be poured into ingots and left to cool. From there, a saw can cut these ingots into thin wafers, process them, and use them in a panel. However, polycrystalline panels are less efficient than monocrystalline panels, which is why many prefer to go for monocrystalline varieties.

To manufacture monocrystalline panels, the melted silicon not only needs to maintain a high temperature but also requires the use of the Czochralski process, where a seed crystal is dipped into a rotating solution of molten silicon and slowly drawn out. This process is not only time-consuming but also consumes a vast amount of energy during the process, which, if done in China, will be sourced from fossil fuel plants. 

But even if the manufacture and transportation of solar panels are not included in the carbon equation, the eventual recycling of solar panels also presents problems. Old panels can’t simply be fixed up and made to work again, and the silicon in old panels cannot be melted down and used in new panels. This means that future panels which get recycled will likely need energy-intensive processes to turn them into usable materials.

What does this mean for solar panels of the future?

The carbon impact from renewable sources is never easy to calculate, especially when data gathered around the subject is selectively chosen to ignore critical aspects of a renewable’s lifetime, such as manufacturing, deployment, and eventual disposal. For example, wind turbines in active use have virtually no carbon footprint if looked at in their immediate environment, but if the manufacture and installation of that turbine were considered, it would be significantly higher than most would think.

The exact same applies to solar panels, and those who push for solar energy are actually doing the environment more harm by not being open and honest about its climate impact. This is also seen with carbon capture technologies which claim to be the solution to a low-carbon future. However, when actually analysing those projects, it quickly becomes evident that their capabilities to trap carbon are often limited but generally insignificant when looking at global CO2 emissions.

In the case of solar panels, if the true carbon impact cannot be fully understood, then deploying solar panels en-masse as a solution against climate change could be potentially devastating. By encouraging a whole generation to switch to solar energy, whose carbon emissions are not so different to hybrid fossil fuel systems (with direct carbon capture), it is possible that massive amounts of public and private funds go to waste while potentially impeding technologies that could have had more impact if they had access to those funds. 

Overall, it comes as no surprise that carbon levels from solar panels are far greater than originally thought, and if the world can learn anything from this report, it’s that anything made in China, whether that’s a physical product or data, can never be fully trusted.

A Balanced View on Solar Energy's Future

While the recent report on solar panels' carbon intensity raises valid concerns, it's essential to consider the broader context. The IPCC's AR6 report emphasises the need for a multifaceted approach to climate change mitigation. Solar energy, despite its challenges, remains a vital part of the global renewable energy strategy.

The key lies in continuous innovation, transparency, and collaboration. By understanding the true carbon impact and working towards reducing it, solar panels can still play a significant role in a sustainable energy future. The global community must come together to address the challenges, invest in research, and implement best practices to ensure that solar energy continues to be a viable and environmentally responsible option.

The Global Perspective on Solar Panels and Climate Change

The Intergovernmental Panel on Climate Change (IPCC) has been actively assessing the global climate situation, and its Sixth Assessment Report (AR6) provides valuable insights into the mitigation of climate change. The report, released in stages between August 2021 and April 2022, culminated in the Synthesis Report on 20 March 2023. This comprehensive assessment offers a scientific basis for understanding climate change and its impacts, including the role of renewable energy sources like solar panels.

According to the IPCC's AR6 report, the mitigation of climate change requires a multifaceted approach, considering not only the immediate environmental impact but also the entire lifecycle of renewable energy technologies. This aligns with the findings of the recent report on solar panels, shedding light on the complexities of assessing the true carbon impact of solar energy.


By Robin Mitchell

Robin Mitchell is an electronic engineer who has been involved in electronics since the age of 13. After completing a BEng at the University of Warwick, Robin moved into the field of online content creation, developing articles, news pieces, and projects aimed at professionals and makers alike. Currently, Robin runs a small electronics business, MitchElectronics, which produces educational kits and resources.