Lines of enquiry: holistic and ethical approaches for end-of-life renewable energy technologies

UK government statistics show there is currently 17.1 gigawatts of solar capacity installed in the UK across all scales – from rooftop domestic arrays on individual houses to utility-scale farms of over a megawatt (MW) in size.

This represents about 49 million panels, or just under one million tonnes of materials (assuming an average panel size of 350W and 20kg per panel).

As our understanding of the risk of modern slavery and forced labour in the supply chains of ores and minerals grows, there is a significant enslavement risk attached to our decarbonisation. There is also the burgeoning problem of what to do with solar farms at the end of their life.

Slavery and waste

Current PV modules are not designed with circularity in mind, meaning they are difficult to disassemble, repair, refurbish or recycle. Older, silicon-based panels are around 75% glass, by weight, with a solar cell comprising polymers, silicon and a variety of valuable metals. Depending on the manufacturer, these components will be present in varying qualities and quantities, and modern panel designs are changing rapidly as the technology evolves.

China dominates the global solar PV market and accounts for approximately 80% of the world’s solar-grade polysilicon. Of this, 35% is believed to be supplied by state-sponsored forced labour camps in the Uyghur region, as outlined in the 2021 report by Sheffield Hallam University, In Broad Daylight: Uyghur Forced Labour and Global Solar Supply Chains. Even as awareness of this grows, bringing due-diligence challenges and narrowing the choices available to contractors, the dominance of Chinese supply chains means that, in reality, its market can supply panels that meet a range of customer values.

Furthermore, because solar panels are not designed for disassembly or recovery, and are the cheapest component part of a solar installation, the supply chain remains locked into an unsustainable linear model.

The human suffering, raw material extraction and carbon emitted in the manufacture and transportation of these panels currently ends with panels abandoned in landfill sites, and/or with valuable and finite resources leaving the UK market, often long before the end of most panels’ usable life.

The waste handler

Solar PV recycling volumes in the UK are sitting at around 100 tonnes per year, government figures show, which is just under 0.01% of the annual waste electrical and electronic equipment (WEEE) generated in the UK. The small volumes placed on the market mean it is challenging for UK-based recyclers to justify investment in any new infrastructure. Although SOLARCYCLE in the US is leading the way in advanced separation technologies, there is currently no at-scale solar PV recycling infrastructure in the UK.

This is made more difficult by the inability to predict when this waste will be generated. Most panels have an assumed asset life (and warranty) of 25 years, and demonstrably perform well for much longer – up to 40 years. However, since new solar panels are extraordinarily cheap and perform much better than older models, many larger asset owners are now considering wholesale replacement (repowering) of solar panels much earlier than their technical end of life – in some cases, after only 10-15 years.

For now, most end-of-life panels from the UK will be exported to mainland Europe, where a handful of facilities are in operation. It is critical that clients and contractors ask for disassembly strategies now – not in 25 years’ time – to give confidence in the end-of-life market.

The contractor’s perspective

The opacity surrounding where funds for WEEE compliance schemes are allocated is challenging for producers. They are concerned about how much of the money contributed to these schemes goes towards building a meaningful recycling infrastructure in the UK.

How can we ensure that we contribute meaningfully to capacity-building efforts that could foster a more sustainable, circular economy for solar PV panels? Without these systems in place, it remains difficult for contractors to advocate long-term solutions that address both environmental and social concerns.

"The [solar panel] supply chain remains locked into an unsustainable linear model"

Contractors are often constrained by factors such as the size, efficiency, lead-in times and cost of solar panels, which limits their influence in selecting specific products during procurement. For example, heterojunction technology (HJT) panels combine crystalline silicon with thin layers of amorphous silicon, creating a more efficient structure than traditional homojunction solar panels, which are based on a single material (usually crystalline silicon). HJT panels are higher efficiency, degrade at a slower rate and have better performance in low light. However, they are also more expensive and have longer lead-in times than traditional panels, as fewer manufacturers have the capacity to produce them.

The reality is that projects have hard deadlines for delivery, usually because once funding is secured it has to be spent within a particular timeframe. The availability of one panel over another is therefore often a more important factor than cost.

Collaboration is key

Dealing with end-of-life panels involves a complex process of decommissioning, transport, recycling and disposal of non-recyclable parts in landfill. Most recycling consists of glass and metal smelters taking most of the waste.

Despite the high recycling rates of 90% or higher for most panel components, recycling often requires destructive methods such as shredding, which greatly reduces the potential for repairs, refurbishment or recovery of valuable materials.

At the moment, recycling is the standard approach for dealing with decommissioned PV panels, but we question whether recycling is the only path, or whether these materials could have a second life.

The CIRCUSOL Network, which brings together 15 partners from seven European countries to develop business solutions for the circular economy in the solar power sector, estimates that around two-thirds of faulty modules could be repaired or refurbished, potentially diverting about 50% of PV waste from being recycled.

CIRCUSOL seeks collaboration from the PV supply chain to formalise the reuse, repair and refurbish value chains in the industry. These solutions would extend the life cycle of materials and reduce energy expenditure during the recycling process. However, policy needs to recognise the value in reuse and include second-hand panels within incentive schemes.

Clients and contractors need to work with the PV industry to drive more holistic approaches that consider the whole life cycle of materials, allowing us all to become custodians of material resources. We need to keep materials at their highest value, reduce extraction of raw materials and extend the life cycle of materials already in existence.

From theory to practice

This article was prompted by a whole-life carbon assessment of an 11.5MW solar farm that is currently being installed in north-west England. The client’s expectations and the contractor’s willingness to work with the client has led to a deeper exploration and understanding of the solar farm’s impact and has started to drive some practical changes within the supply chain.

Of equal importance is how our work together has adapted how we address the benefits of solar – together, we have found that the motive of saving carbon is nuanced, and the impacts (human, carbon and cost) are truly ‘baked in’ at the design stage.

Robust data to complete accurate whole-life carbon assessments is scarce and assumptions have to be made at every stage. Before we get to these calculations, though, we are asking that design teams, clients or consultants consider the impacts of their project more broadly. Where is their red-line boundary of impact or responsibility?

This article has been written collaboratively by Dr Georgiana Allison FIEMA, head of sustainability at Lancaster University, Ana Costa, professor of sustainable architecture at Lancaster University, Anne Johnstone AIEMA, head of ESG at Vital Energi, and Dr Charlotte Stamper, strategic partnerships manager at EMR Renewables