Solar photovoltaic technology is revolutionising the way we live worldwide. It is increasingly popular as a renewable energy source and has been supplying a growing percentage of the electricity demand over the last decade in a number of countries. The World Economic Forum’s 2021 Energy Transition Index stressed the potential of solar technology to better the lives of people in Sub-Saharan Africa, where it says 44% of the population have no access to electricity. Many believe it is a good part of the answer to the climate-and-energy crisis in South Africa, as South Africa has plenty of radiative energy to harness, receiving, on average, approximately 2 500 hours of sunlight per year.
With tax incentives about to be introduced here in SA for going solar, the market for solar panels is bound to soar and the high costs of purchase and installation are likely to drop in the near future.
But, with solar technology becoming more widespread in the country, it’s time both business and consumers start to ask some more questions about the ways in which solar panels are produced.
Sun energy itself is clean and free, but what about the manufacturing processes and conditions in which solar panels are produced? Are they as sustainable – and socially just – as possible?
We’ve looked into the issue here in South Africa, and our research shows few if any local suppliers or installers have any answers for these questions: local SA solar manufacturer Art Solar and reseller Sustainable.co.za, for example, have not responded to our questions. This makes claims of sustainability rather thinner than they need be.
We’re not arguing that these issues should stop consumers from installing solar panels. The climate emergency demands that fossil fuel emissions be at least halved in the next decade to avert dangerous levels of global heating, and that ambition demands renewable energy investment around the world should be scaled up at least six-fold to help avert catastrophic climate outcome, according to the UN Intergovernmental Panel on Climate Change. But we do believe there’s a great opportunity now to pressure the industry to stop resting on its laurels and expand its conception of sustainability.
So what sustainability issues are posed by solar panels? Let’s start by dismissing a myth often circulated by renewable energy naysayers – the energy return on investment of solar. The myth is that the advantages of solar energy are outweighed by the fossil energy used in their manufacture. Is this true?
The facts show that the mining and processing of primary materials, i.e. silicon, aluminium and glass required to produce solar panels call for considerable amounts of heat from electricity, which is often, but need not be, produced using fossil fuels. Silicon is the base material for most photovoltaic solar cells, which make up the panels, given its ability to conduct electricity at high temperatures. Silicon, required in an oxidised form, is mined from quartz sand and this process often greatly contaminates the environment and releases greenhouse gases. The amount of emissions released during this process differs between countries and their manufacturing systems. There is talk of replacing sand with glass in an attempt to be more environmentally friendly. As it stands, Norway is at the forefront of efforts to make silicon production cleaner.
China, the country with the highest production in solar panels, has demonstrated the extent of hazardous pollution from polysilicon (a refined form of silicon) manufacturing. According to recent research by the German Federal Environment Agency (UBA), Chinese panel production emits up to 40% more CO2 than its counterparts in Europe.
Of course, solar-generated electricity can power a solar module foundry as well as fossil-generated power. Renewable energy can replace fossil-fuel energy generation in manufacturing panels. The question is whether this method is widely enough used!
In general, depending on how they have been manufactured and where they are installed, photovoltaics are able to generate the amount of energy used in their production within five to 25 months of their use: taking one to four years in the US, according to the US NationalRenewable Energy Lab, or one to 2.5 years in European conditions.
What other waste products are released during manufacturing?
Throughout the processing of silicon, various toxic chemicals are used and released, with silicon tetrachloride being the most significant. When it reacts with humidity in the air it produces hydrogen chloride which notably hampers human health. The data shows that each ton of polysilicon produced creates at least four tons of silicon tetrachloride liquid waste. Poorly regulated solar manufacturers in China, for example, were known to dump these chemicals and others near villages thus contaminating the soil and groundwater. One would like to believe this is no longer tolerated given the stricter regulations imposed by first-world countries, and increasingly strict environmental regulation in China.
Ideally, silicon tetrachloride should be recycled to produce more polysilicon for manufacturing. It requires practice and regulation but it is feasible.
Are the embedded heavy metals in solar panels toxic?
There is debate over the heavy metals solar panels contain. This has become a worry for farmers in Australia and would be a concern in South Africa where food resources could be compromised by heavy-metal leachate. The metals often used in panels are copper, lead, cadmium telluride (CdTe) and traces of arsenic. Studies performed by the Stuttgart Institute for Photovoltaics and the Institute for Sanitary Engineering, Water Quality, and Waste Management state: “Contrary to earlier assumptions, the result shows that pollutants such as lead or carcinogenic cadmium can be almost completely washed out of the fragments of solar modules over a period of several months, for example by rainwater. Both cadmium and, as we know lead exposure, can lead to serious health complications. On the other hand, First Solar, one of world’s ten largest solar manufacturers insists that CdTe is a stable compound and that its technology is safe:
“More than 50 researchers from leading US and international institutions have confirmed the environmental benefits and safety… over its entire life cycle.”
Recycling solar panels
According to a recent assessment, “many [solar panels]are already winding up in landfills [many in developing countries], where in some cases, they could potentially contaminate groundwater with toxic heavy metals such as lead, selenium and cadmium.”
Researchers in Japan, Europe and the US have been working on solar panel recycling for several years. Two types of PV recycling technology are now commercially available. The three main materials of the panels, aluminium, glass and plastics can all be recycled with advanced machinery. Research firm Rystad estimates the recyclable materials in old solar modules will be worth $80 billion in recoverable assets by the year 2050. These processes cannot be rolled out fast enough, and local installers should be assuring us that decommissioned panels will be processed in this way.
Water and transport footprints
Solar panels do not use water to generate electricity, but the manufacture of solar components does: All the chemical reactions during PV module manufacture require water. The amounts differ considerably depending on the country and manufacturer. The disposal of the wastewater needs careful attention, as already pointed out, as it may contaminate freshwater resources as was the case in 2011 in China.
The emissions from transportation may be significant. This obviously depends where the raw materials are sourced to, where the panels are manufactured, and where they are later installed. There are a number of global brands of solar panels available in South Africa, but there is currently only one local photovoltaic manufacturer, Art Solar. Most modules and panels travel considerable distances before being installed, which given the carbon-intensive nature of most transport, does add to the carbon footprint.
Labour standards and regulations
It’s dismaying that solar industry discussions of sustainability all too rarely extend to the wellbeing of workers and communities. But human rights should be implicit to sustainability.
In recent years, there has been growing concern over reported human rights abuses in the form of forced labour in the polysilicon manufacturing plants in China’s Xinxiang region, where almost two thirds of the world’s solar-grade polysilicon is produced. This concern is growing given the rising global demand for solar energy. It obviously raises huge implications for the purchasers of this raw material in terms of reputational risk, for example. The US imposed sanctions in 2019 on textile goods made from Xinjiang cotton and then in 2021 on key solar panel material from Chinese-based Hoshine Silicon Industry Co, over forced labour allegations.
Emerging lower impact technologies
Up until now traditional rooftop and utility-scale solar panels have flooded the solar market. Emerging solar technologies not only promise improved aesthetics, flexibility and lightness, but also greater resilience to the elements and energy efficiency. A highly anticipated technology is solar thermal fuels (stfs) that can potentially store heat energy at room temperature for up to 18 years by energising the internal configuration (an isomeric reaction) of the fuel molecules.
Solar technology in the form of solar panels is obviously an excellent energy alternative in a country blessed with much sunlight, as many businesses and consumers with PV installations already know. But the technology’s own impacts, though far smaller than those of fossil fuels, should still not be
Sustainability should be defined in terms of a full spectrum of ESG (environment, social, governance) issues: all forms of pollution, labour and human rights and health and safety issues from mine to installer; corporate governance and responsible corporate citizenship. Companies like Tesla may have achieved remarkable results in transforming the automotive market, but cannot and should not be given a free pass on labour and corporate governance issues.
In an already crowded SA solar market, this is an opportunity for those businesses willing to take these issues seriously to differentiate themselves from competitors, and to put pressure on manufacturers to demonstrate their human rights credentials.
Authors: Frances Aron and David Le Page
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