The rapid expansion of photovoltaic (PV) technology has led to increasing attention on end-of-life management for solar modules. With operational lifetimes typically ranging from 25 to 30 years, the first wave of deployed systems is now reaching retirement, necessitating efficient recycling strategies to recover valuable materials and mitigate environmental risks. The handling of end-of-life PV modules varies significantly by technology and region, with silicon-based panels dominating the market, followed by thin-film technologies like cadmium telluride (CdTe) and copper indium gallium selenide (CIGS).

Silicon wafer recovery is a critical component of PV recycling due to the high material value and energy-intensive production of silicon. The process begins with mechanical shredding to remove the aluminum frame and junction box, followed by delamination to separate the glass, polymer layers, and silicon cells. Thermal or chemical treatments are then employed to break down the ethylene-vinyl acetate (EVA) encapsulant, which binds the layers. Once isolated, silicon wafers can undergo etching to remove anti-reflective coatings and metal contacts, allowing for potential reuse in new modules or other applications. However, impurities and microcracks often limit the quality of recovered silicon, necessitating further refinement.

Glass separation presents another challenge, as it constitutes up to 75% of a silicon module’s weight. High-purity glass can be recycled into new solar panels or construction materials, but contamination from EVA residues or metal traces reduces its usability. Advanced sorting techniques, including electrostatic separation and infrared spectroscopy, improve glass purity, though cost remains a barrier to widespread adoption.

Thin-film modules, such as CdTe and CIGS, require specialized chemical processes due to their layered structures and hazardous constituents. CdTe modules contain toxic cadmium, demanding careful handling to prevent environmental release. Hydrometallurgical methods, involving leaching with acids or other solvents, are commonly used to dissolve and recover cadmium and tellurium. Tellurium, a rare and valuable material, is particularly sought after for reuse in new PV modules. Similarly, CIGS modules undergo leaching or pyrolysis to separate copper, indium, gallium, and selenium. Indium and gallium are critical materials with limited supply, making their recovery economically attractive. However, the complexity of these processes increases costs compared to silicon recycling.

Recycling policies for end-of-life PV modules differ markedly between the European Union (EU) and the United States. The EU’s Waste Electrical and Electronic Equipment (WEEE) Directive mandates producer responsibility, requiring manufacturers to finance and organize collection and recycling programs. This extended producer responsibility (EPR) model has driven high recovery rates, with some countries achieving over 90% collection efficiency. The EU also enforces strict material recovery targets, pushing innovation in recycling technologies.

In contrast, the U.S. lacks federal regulations specifically for PV waste, leading to a patchwork of state-level initiatives. Some states, like Washington and California, have implemented their own PV recycling requirements, but enforcement and participation remain inconsistent. The absence of a national EPR framework results in lower recycling rates, with many end-of-life modules ending up in landfills. Industry-led programs, such as those by the Solar Energy Industries Association (SEIA), aim to improve voluntary recycling efforts, but scalability remains a challenge without regulatory support.

Economic factors further influence recycling adoption. In the EU, policy-driven incentives and economies of scale have reduced processing costs, whereas in the U.S., the financial burden often falls on end-users, discouraging participation. Additionally, the EU’s circular economy strategy prioritizes material recovery, while the U.S. focuses more on cost competitiveness, sometimes favoring landfill disposal over recycling.

Technological advancements are gradually improving the feasibility of PV recycling. Automated sorting systems enhance material separation efficiency, while novel chemical processes reduce energy consumption in metal recovery. Research into direct module refurbishment and repurposing for secondary markets also shows promise in extending product lifespans before recycling becomes necessary.

Despite progress, challenges persist. The variability in module designs complicates standardized recycling processes, and the low concentration of valuable materials in some thin-film technologies affects profitability. Furthermore, the environmental benefits of recycling must be weighed against the energy and resource inputs required for processing.

In summary, end-of-life PV management requires tailored approaches for different technologies, with silicon wafer recovery and glass separation being central to silicon modules, while CdTe and CIGS demand specialized chemical treatments. Policy frameworks play a decisive role, with the EU’s regulatory-driven model outperforming the U.S.’s fragmented approach. As PV deployment continues to grow, harmonized regulations and technological innovation will be essential to establishing sustainable recycling ecosystems worldwide.