PVTIME – Solar energy is one of the fastest growing sources of clean energy. As more and more solar panels are produced and installed around the world each year, the question of what to do with old panels arises. Solar panels have a long lifespan of around 30 years, but many panels have been used in solar installations for decades and it is only a matter of time before large numbers of them reach the end of their life. And the recycling process has now attracted much more attention from the government, the Renewable Energy Institute and investors, as it is set to scale up rapidly.
A huge number of solar panels waiting to be recycled
As panels reach the end of their useful life, or as crystalline silicon solar panels are replaced by other types of higher performance products, panel waste will continue to accumulate as more and more panels reach the end of their useful life each year.
Around 8 million tonnes of end-of-life solar panels could be generated globally by 2030. By 2050, that number could reach 80 million, according to the International Renewable Energy Agency (IRENA), while the US will contribute 10 million tonnes of waste to this 2050 total.
According to China’s National Energy Administration, newly installed solar power capacity in the first quarter of 2023 was 33.66GW, up 154.8% year on year, including 15.53GW of centralised solar power plants and 11.83GW of distributed solar power projects. The cumulative installed capacity of solar power generation reached 425GW by the end of the first quarter of 2023. With such a rapid increase in installation volume, about 1.5 million tonnes of solar panels will need to be recycled in China in 2030. By 2050, the figure will rise to 20 million.
In fact, the demand for recycling will come earlier than expected, as weathering and installation errors are now causing end-of-life issues, and some consumers and solar power plant operators may choose to upgrade their panels before the end of the warranty period or to take advantage of technological improvements.
Solar panel recycling is crucial for future
Solar power is an alternative way of providing energy with less carbon dioxide emissions, which is positive in terms of preventing the environment from rising by 1.5 degrees Celsius. This is the main reason for the exponential growth of solar power and end-of-life panels, as the recycling process is a relatively new concept.
However, prior to proper recycling processes, old panels, like any manufactured product, are starting to become a problem as most end up in landfills where they can release toxins that are harmful to the environment and human health. Heavy metals in solar cells, such as cadmium and lead, can become hazardous waste if not recycled or disposed of properly.
Recycling these panels could reduce landfill, which is associated with various environmental and health problems. By recycling, the harmful materials can be kept out of landfills and the environment. It could also provide a new source of materials, such as heavy metals and rare elements, that would otherwise have to be mined to make new solar panels. These critical materials can be recycled back into new panel products, reducing supply chain constraints and ultimately lowering the cost of solar products. And the rare elements in solar cells, such as gallium and indium, could be conserved as they are valuable materials that are depleted from the environment over time if solar panels could be properly recycled.
According to a study published by the International Renewable Energy Agency (IRENA) in 2016, the value of the raw materials that could be recovered from well-recycled PV modules is estimated to be $450 million in 2030 at 2016 prices and more than $15 billion in 2025, which is equivalent to the value of the raw materials currently required to produce 60 million new modules.
Solar panels can be reused and recycled
There are three main types of recycling for solar panels, re-use, mechanical recycling and chemical or thermal recycling.
Reusing solar panels, either directly or after refurbishment, is another way of diverting them from landfill. It gives solar panels a second chance to generate clean energy in a variety of locations, especially in situations where they are not connected to the grid, such as electric vehicle charging stations. Otherwise, regulatory requirements, including grid connection rules, fire, building and electrical codes, need to be considered when planning for solar panel reuse. Nevertheless, the reused solar module will eventually end up in component recycling facilities.
An ideal recycling system would recover as much material as possible from solar panels. There are various methods of recycling solar panels, which may involve some or all of the following three steps. First, the frame and junction box are removed. Second, the glass and silicon wafers are separated by thermal, mechanical or chemical processes. Thirdly, the silicon cells and special metals such as silver, tin, lead and copper are separated and cleaned, using chemical and electrical processes where necessary.
Although there are different solar panels made of different types of solar cells, they are made from similar components, including silicon solar cells, glass sheets, polymer layers, metal frames, copper wires, plastic junction boxes and other materials, with glass accounting for about 70%, aluminium 18%, silicon materials 3.5%, non-ferrous copper 1.5%, rare metals about 1%, encapsulant films 6%.
Many core components are recyclable. Metal trackers and cooper wire can be recycled and reused, and the plastic box is easily recyclable. The glass can be recycled in its well-established industry.
Silicon cells are slightly different recycling processing, as the wafers are usually reused by melting them down and recovering the silicon and various metals inside. And polymer films, used to seal crystalline silicon solar cells which currently account for most of the solar panel market, make recycling and panel disassembly difficult as high temperatures are often required to loosen the adhesive.
Why solar panels are difficult to recycle
The components of solar panels are not difficult to recycle, but separating them from different parts of a panel and recycling them separately is a complex and expensive process. According to the National Renewable Energy Laboratory (NREL), it costs an estimated $15 to $45 to recycle a panel, compared to $1 to $5 to landfill it. And because of the high cost, old panels end up in landfills.
The situation is similar in China, especially for the large number of distributed PV systems, which account for more than 1/3 of the total installed capacity. The old panels are spread across dozens of cities in the country, on the rooftops of tens of millions of buildings, and the decentralised recycling process and transport costs are much higher than expected.
Changes in the value of the raw materials used in solar panels are another factor. As of May 2023, the price of silicon in China has fallen by 30% from its 2022 peak of 320,000 yuan per tonne. Recyclers are reluctant to do business at the same cost. And the high-value silver paste in HJT cells is gradually being replaced by electroplated copper, which will further reduce the profitability of future module recycling.
Supports are needed for panel recycling
Policy support and investment are crucial for scaling up solar panel recycling. Modest government support could accelerate the growth and adoption of the recycling market. A PV recycling plan is needed for China. There are no specific regulations for end-of-life PV modules and recycling processes. During the dismantling process, the control of environmental risks is still at an exploratory stage and no mature standards have been introduced. The China Photovoltaic Industry Association has proposed a PV Module Recycling Working Group to promote the technological progress and industrialisation of module recycling, and many institutions are working on recycling standards and making a detailed plan to achieve their recycling targets.
At present, China has completed the construction of a pilot PV recycling line with a processing capacity of one thousand tonnes. And a PV module green recycling base built by Yingli Energy in Li County, Baoding, is the first crystalline silicon PV module demonstration line based on the physical recycling method in China, setting an example for evaluation method, industry standard and policy proposal, as well as technical innovation.
Meanwhile, investment can promote recycling technology and reduce costs. According to the PV Committee of the China Green Supply Chain Alliance (China ECOPV Alliance), solar panel recycling will be a new industry that attracts investment and is expected to join forces to address recycling issues. The Alliance is working with its members to create a robust recycling network to ensure that the clean energy economy remains sustainable for years to come.
The commercialisation of recycling to economically recover most of the components of a solar panel is planned, and a PV recycling network with intelligent systems is feasible to help the industry provide end-of-life management services to solar and storage installers, project and system owners, developers, distributors and other parties, making solar a more sustainable piece of the clean energy puzzle.