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Striving for Sustainable Solar

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Energy Global,

Despite the scepticism renewables have faced over the past few decades, they continue to become increasingly competitive in the energy landscape. In particular, the solar energy industry has seen an extremely rapid development in the past decade. In 2020 alone, over 127 GW of new photovoltaic (PV) power generation capacity was installed, leading to the total global PV power generation capacity of 707.5 GW (702.9 GW on-grid and 4.584 MW of off-grid)1 at the end of 2020. This means more than one-fifth of renewable energy in the world today is generated by PV technology.

Solar boom

The development of the PV industry in the 20th Century had mainly been fuelled by technological advances and the needs of a few niche markets, such as space applications, which required an autonomous and lightweight power source. The material and fabrication costs of manufacturing solar cells were very high in the 20th Century; however, this was not an immediate concern at the time because their main applications, space projects, were not considered profitable anyway.

On the other hand, the recent ‘solar boom’ has been driven by technical advances in PV technology which have allowed for not only the optimisation in gathering and producing energy, but also a reduction of its associated costs. According to the International Renewable Energy Agency’s (IRENA) recent report2, the global weighted-average total installed cost of utility scale solar PV fell from US$4731/kW to US$883/kW between 2010 and 2020. Over the same period, the levelised cost of electricity from utility scale solar PV also fell by 85% between 2010 and 2020, recording US$0.057/kWh. This figure is comparable to that of coal-fired power generation (which is the cheapest fossil-fuel competitor) available in 2020 (US$0.05/kWh). Given the cost savings over fossil fuels projected in the years to come, alongside international efforts to respond to climate change, the rapid growth of global solar PV capacity is expected to continue for the foreseeable future.

‘Dying’ solar panels

However, whilst this should be welcome news in view of the energy transition, the already large and increasing number of solar panel installations inevitably leads to a problem: What happens to solar panels when they reach end-of-life (EOL)? So far, EOL disposal of solar panels has not caused too many concerns: solar panels only started being widely deployed in the early 2000s, and the industry standard lifespan of solar panels is approximately 25 – 30 years (although many believe that the actual lifespan may be as long as 35 – 40 years). Given that most of the solar panels in the world were installed in the past decade (2011 – 2020), there will likely be a sudden increase in the number of dead solar panels starting from mid-2030s. To give a rough idea, PV panels installed in the past decade provide 640 225 MW total capacity, which is equitant to over 2 billion 300 W solar panels.

EOL management of solar panels

Some may think the mid-2030s timeline is still too early to worry about EOL management of solar panels. However, there are many good reasons why this issue should start being taken more seriously now. The good news is that many governments have already started introducing frameworks for recycling, reusing and, if neither is possible, disposing of dead solar panels. For example, in the UK and many European countries, collection, recycling, and recovery targets for all types of electrical goods, such as solar panels, are set according to the Waste Electrical and Electronic Equipment Directive (WEEE Directive). Still, it is questionable whether the capacity of the existing recycling facilities dedicated to electrical and electronic waste would be able to cope with the ever-increasing volume of solar panel waste. Moreover, conventional recycling processes for general electrical and electronic waste may not be able to deliver the best material recovery rate for solar panel waste. With the rise of high-efficiency PV cells made of novel semiconductor or organic materials, it is also questionable whether conventional electronic waste recycling and disposal processes, which are designed mainly with silicon electronics in mind, would be able to safely handle novel PV materials, some of which are known to be toxic to human health.

Material recovery

But why is there a need to worry about how to reuse and recycle EOL solar panels and their parts? Although the most obvious answer to this question would be to minimise the environmental impact that such large volumes of solar panel waste can have on the planet, this is not just an environmental issue. Solar panels are made of many components, including PV cells (electricity-producing devices), electrical connections, and support frame, all of which contain materials that can be reused or extracted for further use.

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