The C2C-PV project is transforming solar technology as we know it to deliver a fully sustainable, circular process for solar panels.

What if solar panels weren’t just clean in use – but clean in origin, reuse, and afterlife? That’s the question driving the C2C-PV (Cradle-to-Cradle Design of Photovoltaic Modules) project. The project is funded through a Consolidator Grant by the European Research Council and is led by Dr Ian Marius Peters at the Helmholtz Institute Erlangen-Nürnberg (HI ERN).

As the world races to deploy terawatts of solar energy, a troubling challenge looms: while solar panels help decarbonise the grid, most end up as waste. Designed for resilience, today’s modules resist separation. Laminated, fused, and glued into permanence, they were never meant to come apart. C2C-PV aims to change that.

This project doesn’t set out to improve recycling for existing module designs. It flips the problem. Instead of adapting recycling systems to rigid architectures, it rethinks the module itself. Every material, every interface, every assembly decision is reimagined for one goal: perpetual reuse.

At its core, C2C-PV is a design revolution disguised as photovoltaics. It’s an engineering blueprint for circularity – a solar panel that can be built, used, unbuilt, and built again, over multiple generations. Not only does this reduce waste and ease pressure on critical raw materials, it redefines what sustainability means in energy technology.

Spanning five years, the project combines materials science, device architecture, and lifecycle economics. But its ambition goes further: to spark a new way of thinking about solar energy – one that sees recyclability not as an afterthought, but as a foundation.

Recycling: A design challenge, not a crisis

Solar energy is rightfully hailed as one of the greenest energy technologies in the world. But the conversation around sustainability doesn’t stop at deployment – it increasingly includes what happens when panels reach the end of their service life.

On that front, solar has an encouraging head start. Around 75% of a typical silicon PV module is glass – a material with a well-established recycling infrastructure. Aluminium frames account for another 10-15% – another widely recycled material. These characteristics mean solar modules are not some exotic waste stream requiring bespoke solutions. Much of their mass can already enter existing industrial recycling pathways.

A major and often discussed concern lies in scale. With photovoltaic installations poised to exceed 75 TW of installed capacity by 2050, tens of millions of tons of PV modules will eventually reach end-of-life every year. But it’s crucial to keep this in perspective: even in worst-case scenarios, the cumulative PV waste by 2050 would amount to just 1–2% of global municipal waste and a fraction of waste streams from fossil energy. Unlike coal ash or oily sludge, PV module materials are largely non-toxic and manageable. As recent analyses confirm, this is not a looming crisis – it’s a solvable engineering challenge. And it’s an opportunity.

Recycling solar panels can recover materials that are both energy-intensive to produce – like glass – and economically valuable – like silver. In regions such as the European Union, regulatory frameworks already mandate high recovery rates, setting a clear direction for the industry. But to unlock this opportunity fully, we must confront a core tension at the heart of solar module design: durability versus disassembly.

Solar modules are engineered to endure extreme heat, cold, moisture, and UV radiation for decades. The adhesives, encapsulants, and laminates that protect them also make them difficult to take apart. The art of PV recycling, therefore, is to navigate the trade-off between stability and separability. This is not just a matter of process innovation, but of rethinking design itself.

This is where the C2C-PV project steps in – with a blueprint for a future in which the lifecycle of a solar panel doesn’t end in a landfill, but begins again in a new device.

Perovskites: A circular frontier in solar innovation

As part of its mission to pioneer recyclable photovoltaics, the C2C-PV team has identified solution-processed perovskite solar cells as an ideal testbed. Perovskites have emerged recently as a new material in photovoltaics and have shown unprecedented improvements in efficiency. Unlike traditional silicon modules, which require high-temperature and energy-intensive processes, perovskites offer a unique advantage: they can be deposited and disassembled in solution. This opens the door to clean, layer-by-layer recovery of materials using benign solvents – a cornerstone of cradle-to-cradle design.

In a series of recent experiments, the team demonstrated the feasibility of full perovskite cell recycling. Over 99.9% of the cell’s total mass was recovered. The extracted materials, including the perovskite absorber (MAPbI₃), hole transport layers, and transparent electrodes, were purified and reused to fabricate new devices. Fully recycled cells achieved 18% efficiency, while partially recycled ones reached 22%, matching or exceeding the performance of their virgin-material counterparts.

Beyond the technical success, the economic story is equally compelling. A techno-economic analysis revealed that recycling these components not only preserves performance – it has the potential to lower production costs. On the lab scale, a hybrid module using recycled components was assessed to have a cost savings potential of 64% compared to one built entirely from new materials. Projected to industrial scale, this could translate to a 61% reduction in material costs, further enhancing the economic viability of perovskites.

A standout finding centres on glass – the substrate that supports the solar stack. Glass is by far the heaviest component in a solar module and, in perovskite devices, it also represents the most energy-intensive element to produce. Reusing it improves the energy return on investment and enhances the climate impact of the resulting device. Moreover, this glass is coated with a transparent conductive layer – often indium tin oxide (ITO) – which significantly increases its value and role in sustainability strategies. In short, reusing or recycling glass is a powerful sustainability lever.

These results underscore that designing for recyclability can do more than reduce waste – it can also accelerate cost parity and reduce environmental impact. The C2C-PV project thus aims to demonstrate that circular design isn’t a compromise – it’s a strategic advantage.

Toward a regenerative solar future

The C2C-PV project stands at the intersection of innovation, sustainability, and necessity. In a world demanding not just clean energy, but responsible energy systems, it offers a new vision – where solar modules are engineered with their second life in mind from the very beginning.

It is a reminder that the sustainability of solar energy doesn’t end with installation. It extends through use, through decommissioning, and into rebirth. The project’s work with perovskites shows that technical performance, economic viability, and full-cycle recyclability are not mutually exclusive – they can reinforce one another.

As the renewable energy landscape matures, so too must our design principles. C2C-PV is a step toward a regenerative solar future: one that doesn’t just power the planet, but preserves its resources for generations to come.

Please note, this article will also appear in the 22nd edition of our quarterly publication.