What happens when solar panels die?

By the end of 2024, the world is set to achieve a remarkable milestone with nearly 2,000 gigawatts of solar generation capacity in operation. 

This surge in renewable energy has been made possible by solar panels, which are primarily composed of materials like silicon, glass, various polymers, aluminum, copper, and an array of other metals designed to harness the sun's energy. 

Generally, these panels are expected to last for up to 30 years before needing replacement, but the question looms: what happens to all the materials when the current generation of solar panels becomes obsolete? Are we truly prepared for the consequences of this looming waste crisis?

Understanding Solar Panel Lifespan

While it's widely accepted that solar panels last around 30 years, the reality is more nuanced. Garvin Heath from the National Renewable Energy Laboratory (NREL) explains that while 30 years is the industry standard, many panels experience higher failure rates early in their lifecycle due to manufacturing or installation faults. 

In midlife, the failure rates drop significantly, but as panels approach their three-decade mark, issues arise, primarily due to external factors like extreme weather. However, even in their declining years, fewer than one percent of operational panels typically fail, indicating that many can still generate power effectively.

What Diminishes Solar Panel Performance?

The primary threats to solar panels’ longevity stem from environmental conditions. Weather extremes—like hail, heavy winds, or severe temperature fluctuations—can cause irreversible damage. 

When panels break, repairing them often becomes economically unviable, especially if the damage is superficial. Interestingly, panels that are removed after 25 or 30 years may still be operational, yet they are often replaced not due to functional failure but rather economic considerations.

The Economics Behind Replacement

The crux of the issue lies in efficiency loss. As panels age, their ability to convert sunlight into electricity diminishes, often due to the degradation of laminated layers that help maintain the integrity of the solar cells. 

Manufacturers typically offer warranties for 30 years, promising that their panels will maintain at least 80% efficiency. As panels approach the end of their warranty, operators may find it more cost-effective to replace them, even if they still perform adequately. 

This is particularly pressing for large commercial farms, where maximizing output is crucial.  Matt Burnell, founder of ReSolar, provides insight into the economic rationale behind this decision. 

For instance, a 10-megawatt solar farm might have previously operated at full capacity with older technology, but advancements in solar efficiency mean it’s financially advantageous to replace older panels with newer, more efficient ones. Consequently, even operational panels may end up in the waste stream due to economic pressures rather than actual failure.

The Waste Crisis

Currently, only about one in ten solar panels is recycled, with the majority ending up in landfills. The lack of standardization for tracking and disposing of decommissioned panels exacerbates the problem. As solar installations proliferate—particularly in places like California, where incentives have led to a solar boom—an influx of obsolete panels threatens to overwhelm waste management systems.

Existing legislation around solar panel disposal is inconsistent at best. While federal regulations classify decommissioned panels as either solid or hazardous waste, there’s a significant gap in comprehensive recycling mandates. This leaves many panels—especially those containing toxic materials—redirected to specialized landfills instead of being effectively recycled.

In the UK and Europe, the Waste from Electrical and Electronic Equipment (WEEE) directive mandates that manufacturers collect and recycle discarded panels. This regulatory framework aims to prevent a landfill crisis but may unintentionally incentivize recycling over repurposing, leading to further waste of potentially functional panels.

Recycling Challenges and Solutions

The process of recycling solar panels generally follows two approaches: mechanical and chemical. Mechanical recycling, while simpler, often results in lower recovery rates of valuable materials like silicon and silver. On the other hand, thermal and chemical methods can effectively separate materials but may involve complex processes that drive up costs.

As the International Energy Agency (IEA) points out, the mechanical methods currently employed often compromise material quality. The diversity of materials in solar panels complicates recycling efforts, as manufacturers lack transparency regarding the specific compositions of their products.

Innovative solutions are being explored. For example, a project led by Dr. David Young at NREL is developing solar panels that forego adhesives altogether. Instead, femtosecond lasers are used to bond glass layers, potentially leading to panels that are easier to disassemble and recycle when they reach their end of life.

Looking Forward

The next decade presents both challenges and opportunities for the solar panel industry. With millions of panels set to enter the waste stream, the need for efficient recycling solutions is urgent. While current recycling practices are not yet economically viable, advancements in technology and regulation could change that landscape.

As awareness grows about the environmental impact of solar panel waste, stakeholders from manufacturers to end-users must collaborate to create a sustainable end-of-life solution for solar technology. 

The transition to a circular economy in solar energy is not just desirable; it is necessary to ensure that our commitment to renewable energy does not lead to new forms of environmental degradation.

While the future of solar energy is bright, we must confront the reality of solar panel waste with urgency and innovation. The question of what happens to solar panels at the end of their lifecycle may not have a straightforward answer today, but with concerted efforts in recycling technology and policy reform, we can pave the way for a more sustainable approach to solar energy.