System-Level Design of Photovoltaic Recycling Infrastructure: A Review of Mechanical, Thermal, Chemical, and Laser-Based Technologies

Abstract

This review paper presents a system-level engineering design perspective on end-of-life (EoL) photovoltaic (PV) recycling, addressing a critical gap in the literature that is predominantly focused on material and process-level analyses. A unified framework is developed to evaluate mechanical, thermal, chemical, and emerging laser-based technologies through the lenses of system architecture, process control, and infrastructure integration. The study introduces design-oriented concepts, including optimal processing windows, modular system configurations, and multi-layer control frameworks, to support decision-making in scalable PV recycling systems. Particular emphasis is placed on laser-based recycling (e.g., femtosecond laser technology), which enables non-thermal, high-precision, and interface-selective material separation, representing a paradigm shift towards intelligent and adaptive recycling infrastructures. The paper also highlights the transition from conventional bulk PV processing to precision-controlled, artificial intelligence (AI)-enabled systems, and outlines future research and industrial pathways required to realize sustainable, high-efficiency PV recycling within a circular economy.

1. Introduction

1.1. Research Background and Motivation

The rapid global deployment of photovoltaic (PV) systems has been instrumental in accelerating the transition towards low-carbon energy systems. However, this expansion is accompanied by an emerging challenge: the management of end-of-life (EoL) PV modules. With typical lifetimes of 20–30 years, a significant volume of PV waste is expected within the coming decades [1], necessitating the development of efficient, scalable, and sustainable recycling systems. Addressing this challenge requires not only advancements in material recovery processes but, crucially, the engineering design of integrated recycling systems that consider performance, cost, environmental impact, and circularity.

A typical crystalline silicon PV module consists of multiple tightly bonded layers, including a front glass cover, encapsulant materials (e.g., Ethylene Vinyl Acetate (EVA) [2]), silicon solar cells, backsheet, and supporting structures such as aluminum frames and junction boxes, as illustrated in Figure 1. The strong lamination and material heterogeneity that ensure durability during operation simultaneously pose significant challenges for disassembly and material recovery at EoL [3]. Consequently, the effectiveness of any recycling strategy is fundamentally governed by design decisions related to layer separation (decoupling), process sequencing, and system integration.

Current PV recycling approaches can be broadly categorized into four principal technological pathways (as demonstrated in Figure 2): mechanical, thermal, chemical, and emerging laser-based decoupling techniques. Mechanical methods typically involve dismantling and size reduction processes, enabling partial material recovery but often with limited purity. Thermal approaches utilize high-temperature treatments to decompose encapsulants and separate layers, though they are energy-intensive and may induce material degradation. Chemical processes aim to selectively dissolve encapsulant layers or recover high-value materials with high purity, yet they introduce challenges related to reagent use, waste handling, and process scalability. More recently, laser-enabled technologies have emerged as a promising next-generation solution, offering precise, contactless, and potentially low-damage delamination pathways, particularly when integrated with intelligent control systems.

Despite significant progress in PV recycling technologies, the existing literature is largely dominated by material- and process-level investigations. Several comprehensive reviews have examined individual recycling pathways, including mechanical, thermal, and chemical processes, with a strong emphasis on material recovery efficiency, reaction mechanisms, and process optimization [4,5,6]. While these studies provide valuable insights into specific technologies, they typically treat recycling processes in isolation, with limited consideration of how different processes interact within an integrated system. As a result, key system-level challenges, such as process sequencing, infrastructure design, scalability, operational trade-offs, and integration across the recycling value chain, remain insufficiently addressed. In particular, there is a lack of design-oriented frameworks that support decision-making across multiple processing stages, from module intake and pre-treatment to material recovery and reintegration. This gap becomes increasingly critical as PV waste volumes grow and recycling systems must transition from laboratory-scale demonstrations to industrial-scale infrastructures. Addressing this challenge requires a shift from process-centric analysis towards a system-level engineering perspective, where technologies are evaluated not only based on individual performance, but also on their role within integrated, scalable, and adaptable recycling systems.

The remainder of this paper is structured as follows. Section 1.2 outlines the main contributions and scope of this review. Section 2 presents a comprehensive analysis of PV recycling technologies, including mechanical, thermal, chemical, and laser-based approaches, with a focus on their evolution, design space, and system integration. Section 3 discusses the broader engineering implications, highlighting emerging trends, system-level trade-offs, and future development pathways. Finally, Section 4 concludes the paper by summarizing key findings and outlining directions for future research.

1.2. Scope and Contributions of This Review

Building upon the identified research gap, this review aims to provide a structured and design-oriented analysis of PV recycling technologies. Unlike existing reviews that primarily focus on individual material recovery processes or isolated technological pathways [4,5,6], this work adopts a holistic engineering approach, where recycling technologies are evaluated within the context of integrated system architectures and infrastructure design. The key contributions of this paper can be summarized as follows:

• System-level design perspective: The paper reframes PV recycling as a system engineering problem, emphasizing process integration, infrastructure configuration, and operational trade-offs across the full recycling value chain.
• Unified design space analysis: Mechanical, thermal, chemical, and laser-based technologies are analyzed within a common framework, enabling direct comparison in terms of process control, selectivity, scalability, and system integration potential.
• Introduction of design-oriented frameworks: The study proposes several conceptual tools to support engineering decision-making, including (i) processing window representations for thermal systems, (ii) integrated hybrid process architectures, and (iii) a multi-layer system design framework for laser-based recycling.
• Emphasis on next-generation technologies: Particular attention is given to laser-enabled recycling and AI-driven control systems, positioning them within the broader evolution of PV recycling infrastructures and identifying their potential for precision, adaptability, and high-value material recovery.
• Identification of research and infrastructure gaps: The paper highlights key limitations in current recycling approaches, including challenges related to scalability, system integration, economic feasibility, and adaptability to emerging PV technologies, thereby outlining priorities for future research and industrial development.

1.3. Methodology of the Review

This review adopts a structured narrative approach to analyze the design and integration of PV recycling systems from a system-level engineering perspective. The literature considered in this study was collected from major scientific databases, including Scopus, Web of Science, and Google Scholar, with a focus on peer-reviewed journal articles published primarily between 2015 and 2026.

The selection of literature was guided by relevance to the engineering design, process integration, and system-level performance of PV recycling technologies. Studies focusing exclusively on material characterization without clear implications for process design or system integration were considered less central to the objectives of this review. Priority was given to works that provide insights into process mechanisms, system configurations, techno-economic performance, and scalability. The selected studies were analyzed and categorized into four principal technological domains: mechanical, thermal, chemical, and laser-based recycling. Rather than treating these categories as isolated processes, the analysis emphasizes their role within integrated system architectures, including hybrid configurations and multi-stage recycling workflows. In addition, the review incorporates emerging concepts such as digitalization, adaptive control, and circular economy strategies, including reuse and refurbishment.

The synthesis of the literature is therefore not limited to a descriptive comparison of technologies, but is structured around key engineering design dimensions, including process control, selectivity, scalability, energy efficiency, and system integration. Conceptual frameworks presented in this paper, such as processing windows and multi-layer system architectures, are developed through the interpretation and integration of insights across multiple studies, rather than derived from a single source. This approach enables the identification of design trade-offs, research gaps, and future development pathways.

2. Evolution and Design Space of PV Recycling Technologies

This section reviews the current state of PV recycling technologies from an engineering design, system integration, and infrastructure perspective, with a focus on how different approaches influence overall recycling performance and scalability. Rather than providing a purely process-based comparison, the discussion is framed around design decisions, system architectures, and operational considerations associated with the four principal recycling pathways: mechanical, thermal, chemical, and laser-based decoupling. Emphasis is placed on how these technologies have evolved, the trade-offs they introduce at system level, and their implications for the development of efficient, adaptable, and sustainable PV recycling infrastructures.

While the classification adopted in this work distinguishes PV recycling technologies into four principal categories, mechanical, thermal, chemical, and laser-based, it is important to note that real-world recycling systems are often more complex and involve combinations of multiple processing routes. In particular, industrial recycling pathways frequently integrate pre-treatment operations such as dismantling, delamination, and size reduction, followed by hydrometallurgical or pyrometallurgical processes for material recovery. These approaches are not treated here as entirely separate categories, but rather as specific implementations or sub-domains within the broader chemical and thermal processing frameworks. Furthermore, hybrid recycling systems that combine mechanical, thermal, and chemical stages are increasingly recognized as the most practical and scalable solutions for PV waste treatment. In addition, circular economic strategies such as direct reuse, refurbishment, and remanufacturing are gaining importance, particularly for modules that retain functional value, and should be considered as complementary pathways alongside material recycling.

2.1. Mechanical-Based EoL PV Recycling

Mechanical-based recycling remains one of the most established and industrially accessible pathways for the treatment of EoL PV modules, largely because it is grounded in familiar unit operations, modular plant architecture, and relatively mature materials handling infrastructure. From an engineering design perspective, the central objective of a mechanical recycling system is not merely to break down the module, but to do so in a manner that structures the downstream material flow into recoverable fractions with acceptable purity, throughput, and safety.

In this context, system performance is governed by a sequence of design decisions concerning feed handling, pre-processing, fragmentation intensity, particle size control, separation logic, containment, and process automation [7]. Figure 3 illustrates a representative system-level configuration of a mechanical PV recycling line. It should be noted that this configuration does not correspond to a single specific industrial facility but rather represents a conceptual synthesis of commonly reported unit operations and process layouts found in mechanical recycling systems [7,8,9,10,11,12,13]. The process starts with a mechanical line in which EoL PV modules pass through intake, frame and junction box removal, shredding [8], granulation, screening, magnetic separation, eddy-current separation, air classification, and final material collection. This type of layout reflects a classic process engineering philosophy in which disassembly and comminution are integrated with physical separation stages to progressively liberate and sort material streams.

A key strength of mechanical recycling lies in its compatibility with continuous or semi-continuous processing. The design shown in Figure 3 highlights the importance of conveyor-linked material transfer, distributed actuation, and centralized programmable control, all of which support operational stability and scalability. For PV modules, pre-processing is especially important because aluminum frames and junction boxes represent relatively accessible components with clear economic value and should be removed before intensive fragmentation [9]. This not only reduces mechanical load on the shredding unit but also improves the consistency of downstream particle generation [10]. Once the laminated structure enters primary and secondary size-reduction stages, the engineering challenge shifts towards achieving sufficient liberation of glass, metals, polymers, and silicon-bearing fractions without causing excessive contamination through over-fragmentation. The size-reduction profile therefore becomes a core system design variable: too little fragmentation limits separation efficiency, whereas too aggressive a process increases dust formation, intermixing of fine particles, and loss of material value [11].

The downstream configuration of the mechanical line is equally significant from a system design standpoint. Vibratory screening, magnetic separation, eddy-current separation, and density-based air classification are not isolated devices, but interdependent stages whose effectiveness depends on feed uniformity, particle morphology, moisture state, and the degree of prior liberation [12]. Thus, the design of a mechanical PV recycling system must be approached as a coordinated separation network rather than a simple chain of equipment. In practical terms, this means that particle size windows, belt speeds, rotor settings, airflow rates, and collection bin logic should be selected as part of an integrated optimization problem [13]. Figure 3 supports this perspective by showing how the material flow direction, dust extraction, and control system architecture interact across the full line. Such integration is essential for maintaining safe operation, especially given the presence of glass fines, polymer dust, and metal fragments, all of which can affect equipment wear, filtration demand, and occupational exposure. Accordingly, as discussed by [14], dust extraction and filtration are not peripheral additions but fundamental design elements in the infrastructure of mechanically driven PV recycling plants.

Beyond its operational practicality, mechanical recycling is also significant because it provides a foundation for infrastructure deployment at regional and industrial scales. Its equipment is generally based on mature machinery classes already used in waste processing, electrical equipment recycling, and mineral handling, which lowers the barrier to deployment. However, from a methodological design perspective, maturity does not automatically imply optimality for PV waste. PV modules are highly laminated, brittle–ductile composite products, and their architecture challenges conventional comminution logic. As a result, one of the most important design questions is how to tailor fragmentation mechanisms to the physical structure of the PV module rather than relying solely on brute-force shredding [15]. This has motivated interest in more selective mechanical fragmentation approaches that aim to reduce damage to valuable fractions and improve separation efficiency.

One such emerging approach is high-voltage fragmentation (HVF) [16], shown schematically in Figure 4. In contrast to conventional shredding and granulation, HVF introduces pulsed electrical discharges into a controlled medium, typically water, to induce interface-driven fragmentation within the layered PV structure. From a scientific and engineering design perspective, this is highly significant because the fragmentation mechanism is no longer governed primarily by bulk mechanical shear or impact [16,17,18], but by localized stress generation along material interfaces with differing dielectric and mechanical properties. In laminated PV modules, these interfaces include glass–encapsulant, encapsulant–cell, and cell–backsheet boundaries. The system shown in Figure 4 includes a feed/loading section, pulse generator, insulated containment, upper and lower electrodes, a water-filled fragmentation chamber, output collection, and downstream size classification. Such a configuration reflects a more selective fragmentation philosophy, where the plant is designed to exploit the internal architecture of the module rather than indiscriminately reducing all components into mixed fragments.

From a system-level design perspective, HVF introduces a different set of engineering priorities compared with conventional mechanical lines. The chamber design, dielectric medium, electrode geometry, pulse frequency, voltage range, residence time, and discharge channel control become critical variables affecting fragmentation selectivity and energy transfer [19,20]. The inclusion of sensor monitoring and pulse control, as shown in Figure 4, indicates that HVF systems are inherently more dependent on closed-loop control and process diagnostics than traditional shredding systems [17,20]. This creates opportunities for more precise operation but also demands a stronger methodological framework for equipment design, instrumentation, and safety interlocks. In particular, containment integrity, electrical insulation, water management, and discharge repeatability become central design requirements. The engineering challenge is therefore not only to demonstrate fragmentation, but to develop a robust process platform capable of stable throughput, controlled fragment size distribution, and repeatable liberation of valuable materials across variable PV module conditions.

Overall, mechanical-based EoL PV recycling should be understood as a broad design domain that spans conventional comminution-based plants and more selective fragmentation platforms. The main methodological contribution of this domain is its emphasis on physical disassembly, material liberation, and infrastructure-compatible processing. For the design of future PV recycling systems, the critical issue is not simply whether mechanical treatment is feasible, but how the mechanical system is architected to balance throughput, selectivity, safety, maintainability, and downstream material quality. Figure 3 and Figure 4 together demonstrate that the evolution of mechanical recycling is increasingly shaped by system design thinking: from linear shredding-based layouts towards more controlled, selective, and sensor-informed fragmentation infrastructures tailored to the layered construction of PV modules.

2.2. Thermal-Based EoL PV Recycling

Thermal-based recycling represents a fundamentally different design philosophy for EoL PV systems, in which controlled heat transfer is used as the primary mechanism for material decoupling, particularly targeting the decomposition of encapsulant layers such as EVA [21]. Thermal recycling systems are not simply defined by furnace operation, but by the integration of thermal, fluid, and process control subsystems that collectively determine material recovery efficiency, energy consumption, emissions management, and operational safety [22]. Figure 5 illustrates a representative pilot-scale thermal recycling system, highlighting the key design elements including feed handling, pre-processing, thermal treatment chamber, gas management, heat recovery, cooling, and system control infrastructure.

At the core of the system is the thermal treatment chamber, where PV modules are subjected to elevated temperatures typically in the range of 450–650 °C [23] under controlled atmospheric conditions. The primary design objective at this stage is the selective decomposition of polymeric encapsulants without causing excessive degradation of high-value materials such as glass and silicon wafers. This introduces a critical trade-off in system design: higher temperatures and longer residence times improve encapsulant removal but increase the risk of glass softening, silicon damage, and energy inefficiency [24]. As shown in Figure 5, the inclusion of a temperature control unit, sensor ports for real-time monitoring, and defined residence times reflects the need for precise thermal regulation as a central design requirement rather than a secondary operational parameter.

From a system architecture perspective, thermal recycling systems are inherently multi-domain, combining heat transfer, gas flow management, and material handling within a single integrated infrastructure. The presence of a controlled atmosphere within the treatment chamber, whether inert, oxidative, or low oxygen, directly influences decomposition pathways [25], emission profiles, and material integrity. Consequently, the design must incorporate gas handling and filtration subsystems, such as high-efficiency particulate air (HEPA) filters and scrubbers, to capture volatile organic compounds (VOCs) [26], particulate emissions, and potentially hazardous by-products generated during encapsulant degradation. The off-gas outlet and filtration units shown in Figure 5 are therefore not auxiliary components but integral to ensuring environmental compliance and safe operation.

Energy efficiency is another defining factor in the design of thermal PV recycling systems. Given the inherently energy-intensive nature of high-temperature processing, the inclusion of a heat recovery unit, as illustrated in Figure 5, is essential for improving overall system sustainability. Recovered thermal energy can be reintegrated into the heating cycle or utilized elsewhere within the facility [23], thereby reducing operational costs and environmental impact. This highlights an important system-level design principle: thermal recycling plants should be conceived not as isolated reactors, but as energy-integrated process systems in which heat flows are optimized alongside material flows.

The downstream configuration of the system further reflects the importance of controlled process transitions. Following thermal treatment, materials enter a cooling zone, where controlled cooling is necessary to stabilize material properties [27], prevent thermal shock, and prepare outputs for subsequent handling or separation. The design of this stage must account for cooling rates, airflow, and potential re-condensation of volatile species [26]. The separation of outputs into distinct material streams (e.g., glass, metals, and residues) depends on the effectiveness of prior thermal decoupling, reinforcing the interdependence between upstream thermal conditions and downstream material recovery performance.

From a control and safety standpoint, thermal recycling systems require a higher degree of process monitoring and interlock mechanisms compared to purely mechanical approaches. The integration of programmable logic controllers (PLCs), emergency shutdown systems, pressure relief vents, and continuous sensor feedback enables stable operation under high-temperature and potentially hazardous conditions. These elements are central to the engineering design of such systems, as they ensure reliability, repeatability, and compliance with industrial safety standards. The skid-mounted structural configuration shown in Figure 5 also reflects a trend towards modularity, allowing for easier deployment, scaling, and integration into existing waste management infrastructure.

In terms of design methodology, thermal-based PV recycling systems exemplify a process-driven and parameter-sensitive design space, where system performance is governed by the interplay between temperature, residence time, and material response. As illustrated in Figure 6, the effectiveness of thermal treatment cannot be defined by a single operating condition, but rather by an optimal processing window within which encapsulant decomposition is achieved while maintaining the structural and functional integrity of high-value materials such as glass and silicon [28]. This introduces a multi-objective design problem in which recovery efficiency, energy consumption, emissions, and material degradation must be considered simultaneously.

Figure 6 highlights three distinct operational regimes that are critical for engineering decision-making. At lower temperatures and shorter residence times, the system operates in an under-processing region, where incomplete encapsulant removal leads to poor material liberation and inefficient downstream separation. Conversely, at elevated temperatures and extended residence times, the system enters an over-processing region, characterized by excessive energy consumption, increased emissions, and irreversible material degradation, including glass softening and silicon damage. Between these extremes lies an optimal processing window, where encapsulant decomposition is sufficient to enable effective separation [28], while minimizing thermal damage and energy inefficiency. From a system design perspective, identifying and maintaining operation within this window is a central requirement for achieving both technical and economic viability.

This representation reframes thermal recycling as a design optimization problem rather than a fixed process, where operating conditions must be dynamically selected based on module composition, throughput requirements, and system constraints [23,29]. It also underscores the importance of sensing and control strategies, as real-time monitoring of temperature, gas composition, and residence time is necessary to avoid transitions into inefficient or damaging regimes. The inclusion of energy efficiency boundaries and degradation thresholds, as shown in Figure 6, further emphasizes that thermal system design must explicitly account for trade-offs between process intensity and material preservation.

2.3. Chemical-Based EoL PV Recycling

Chemical-based recycling represents a selectivity-driven design paradigm for EoL PV systems, in which material recovery is achieved through controlled dissolution, leaching, and purification processes [30]. This approach shifts the focus from physical disassembly or thermal transformation towards reaction engineering, fluid handling, and separation system integration, where the objective is to maximize material purity and recovery yield while maintaining process safety and environmental compliance. The complexity of PV module composition, particularly the presence of metals, silicon, polymers, and glass, requires carefully orchestrated chemical pathways that are tightly coupled with upstream pre-treatment and downstream purification stages [31].

Figure 7 illustrates a representative pilot-scale chemical recycling system architecture, highlighting the key subsystems involved in reagent storage and dosing, reaction control, fluid transfer, separation, solvent recovery, and waste treatment. At the core of the system is the chemical reactor vessel, where pre-treated PV materials are subjected to controlled chemical environments [32] defined by parameters such as temperature (typically 40–80 °C [30]), pH (acidic [33] or alkaline conditions [34]), reagent concentration, and residence time. The inclusion of sensor networks for temperature, pH, and pressure monitoring, as well as agitation systems and dozing ports, reflects the importance of precise reaction control in determining dissolution kinetics, selectivity, and material recovery.

From a system design standpoint, the effectiveness of chemical recycling is governed by the integration of multiple interdependent subsystems rather than the reactor alone [31]. Reagent storage and dosing units must be designed to ensure accurate delivery of acids, bases, or catalysts, while maintaining compatibility with corrosive environments and enabling safe containment. The fluid transfer system, including pumps, valves, and pipelines, plays a critical role in maintaining continuous or semi-batch operation [35], ensuring uniform mixing and transport of reactants and products across the system. These elements collectively define the process continuity and scalability of chemical recycling infrastructures.

A defining feature of chemical-based systems is the multi-stage separation and purification framework that follows the reaction phase. As shown in Figure 7, solid–liquid separation units (e.g., filtration) are used to isolate undissolved residues, while liquid-phase separation processes such as precipitation, extraction, or ion exchange enable the recovery of high-purity materials, including silicon and valuable metals [36]. The design of these stages must account for factors such as solubility limits, reaction by-products, phase equilibria, and impurity profiles [37]. Importantly, these downstream processes are not independent of upstream reaction conditions; rather, they are strongly influenced by the chemical environment established within the reactor, reinforcing the need for holistic system design and parameter coordination.

Environmental and safety considerations are central to the engineering design of chemical PV recycling systems. The use of reactive chemicals necessitates robust containment strategies, emergency shutdown systems, and secondary containment (e.g., spill bunds), as indicated in Figure 7. Furthermore, waste treatment and neutralization units are essential for managing effluents and ensuring compliance with environmental regulations [38]. The inclusion of a solvent recovery and regeneration unit highlights another critical design principle: circular use of reagents to reduce operational costs and environmental burden. From a system-level perspective, this transforms the process from a linear consumption model into a closed-loop chemical processing system, which is more aligned with circular economic objectives.

Figure 8 extends this perspective by illustrating a hybrid process architecture, where chemical treatment is integrated with upstream physical and thermal pre-treatment stages. This combinational approach reflects a key insight in the design of PV recycling systems: no single process is sufficient to address the full complexity of module architecture. Instead, chemical processes are most effective when applied to pre-conditioned material streams [39], where prior size reduction and encapsulant removal enhance reagent accessibility and reaction efficiency. From a design methodology standpoint, this introduces the concept of process sequencing and modular system integration, where each stage is selected and configured based on its contribution to overall system performance.

The hybrid workflow shown in Figure 8 demonstrates how mechanical pre-treatment reduces module size and complexity, thermal treatment facilitates encapsulant decomposition, and chemical processing enables high-purity material recovery [25]. This layered design strategy allows engineers to allocate functions across different process domains, thereby improving efficiency and reducing the burden on any single subsystem. Importantly, this approach also supports adaptability, as individual modules within the system can be modified or optimized independently in response to changes in PV technology, material composition, or regulatory requirements.

From a design decision-making perspective, chemical-based PV recycling systems are characterized by a series of trade-offs involving reagent consumption, process selectivity, recovery purity, waste generation, and operational complexity. The challenge for engineers is to define system configurations that balance these factors while ensuring scalability and economic viability [40]. This requires not only detailed knowledge of chemical processes but also a systems engineering approach that integrates reaction design, separation technologies, fluid dynamics, and environmental management into a coherent framework. Overall, chemical recycling occupies a critical role within the broader design space of PV recycling technologies due to its ability to achieve high-purity material recovery, particularly for silicon and valuable metals. However, its successful implementation depends on careful system integration, process optimization, and infrastructure design, as illustrated in Figure 7 and Figure 8. By framing chemical recycling within a system-level design methodology, this approach aligns with the objectives of developing efficient, scalable, and sustainable PV recycling solutions.

2.4. Laser-Based EoL PV Recycling: The Future Technology

Laser-based recycling represents a next-generation design paradigm for EoL PV systems, characterized by precision, selectivity, and non-contact material processing. Unlike conventional approaches that rely on bulk mechanical forces or high-temperature transformations, laser-based systems operate through controlled photon–material interactions, enabling targeted layer separation with minimal collateral damage [41]. This approach introduces a shift towards high-resolution, digitally controlled, and adaptive processing infrastructures, where system performance is governed by the coordination of optical, thermal (at micro-scale), and control subsystems.

Figure 9 illustrates a representative pilot-scale laser-enabled PV recycling system, centered on the use of ultra-short pulse lasers, particularly femtosecond lasers, which are increasingly recognized as a transformative technology in this domain. While picosecond lasers also offer advantages in industrial processing, femtosecond laser systems enable non-thermal or “cold” ablation regimes [42,43,44,45], where material removal occurs faster than heat diffusion, thereby significantly reducing thermal damage to adjacent layers. This is especially important for PV modules, where preserving the integrity of silicon wafers, metallic interconnects, and glass substrates is critical for high-value recovery.

From a system design standpoint, the laser recycling platform integrates several tightly coupled subsystems. The beam generation and delivery system, including the femtosecond laser source, beam shaping optics, and focusing elements, defines the spatial and temporal characteristics of the laser–material interaction. These parameters, such as pulse energy, pulse duration, repetition rate, and spot size, directly influence ablation efficiency, penetration depth, and selectivity. The inclusion of a galvanometric scanning head and precision XY positioning stage, as shown in Figure 9, enables controlled and repeatable scanning patterns across the PV module surface, facilitating layer-specific processing strategies such as encapsulant removal or interfacial delamination.

A defining feature of laser-based systems is the integration of real-time monitoring and adaptive control. Vision systems and optical sensors [46,47] provide continuous feedback on process quality, material response, and ablation characteristics, which are fed into a central control system (e.g., PLC or embedded interface [48]). This enables the implementation of closed-loop control architectures, where laser parameters can be dynamically adjusted in response to variations in material composition, surface conditions, or defect states. As indicated in Figure 9, the incorporation of AI-driven control further enhances this capability, allowing for data-driven optimization of processing conditions to maximize precision, throughput, and material recovery quality.

In contrast to conventional recycling infrastructures, laser-based systems are inherently modular, digital, and highly configurable, making them well-suited for integration into intelligent manufacturing and recycling environments. The enclosed processing chamber, extraction system for ablated particulates [49,50,51], and filtration units are essential design components that ensure operational safety and environmental compliance. Furthermore, the non-contact nature of laser processing reduces mechanical wear and contamination, contributing to improved system reliability and maintenance efficiency.

To formalize the design methodology of such systems, Figure 10 presents a multi-layer engineering framework that captures the key elements of laser-based PV recycling from a system-level perspective. This framework emphasizes that successful implementation requires more than selecting a laser source; it involves coordinating multiple layers of design decisions, from input characterization to performance evaluation. At the input level (Layer 1), system design is informed by PV module properties, target recovery objectives, and operational constraints such as throughput and sustainability requirements. These inputs directly influence the selection of laser system parameters (Layer 2), where decisions regarding pulse regime (femtosecond vs. picosecond [43]), scanning strategy, and interaction mode must be aligned with desired material outcomes.

The process execution layer (Layer 3) represents the physical implementation of laser–material interaction, where non-thermal ablation and selective delamination occur. However, unlike static systems, laser-based recycling relies heavily on Layer 4 (monitoring and feedback), where real-time diagnostics ensure process stability and quality assurance. The integration of Layer 5 (adaptive AI control) further elevates the system into a smart, self-optimizing platform capable of learning from process data and adjusting control variables dynamically, as demonstrated by several previous work [52,53,54,55]. Finally, Layer 6 (outputs and performance metrics) provides a structured basis for evaluating system performance, including material separation quality, energy consumption, throughput, and overall system efficiency.

While the studies cited in [52,53,54,55] demonstrate the effectiveness of deep learning and data-driven optimization in laser-based material processing, it is important to note that these approaches have been primarily developed and validated in non-photovoltaic domains, such as metals, semiconductors, and microfabrication systems. Nevertheless, the underlying principles of adaptive control, real-time parameter tuning, and process–response modeling are directly transferable to PV recycling, particularly in the context of layer-selective ablation and heterogeneous material interfaces. However, there remains a clear research gap in the application of AI-driven control specifically tailored to photovoltaic recycling systems. In particular, the development of domain-specific models capable of handling the variability in PV module composition, degradation states, and encapsulation structures has not yet been extensively explored. Addressing this gap represents a key opportunity for advancing laser-based PV recycling towards intelligent, self-optimizing, and industrially scalable systems.

From a design and decision-making perspective, laser-based PV recycling introduces a new set of trade-offs compared with conventional technologies. While it offers unparalleled precision and the potential for high-purity material recovery, it also requires careful consideration of capital cost [56], system complexity, energy input at the micro-scale, and integration with upstream and downstream processes. However, its ability to selectively target interfaces and minimize damage positions it as a key enabling technology for future circular PV systems.

3. Discussion

3.1. System-Level Design Insights and Technological Evolution

The preceding sections have examined PV recycling technologies through the lens of individual processing approaches. However, from the perspective of this study, the central contribution lies not in the comparison of technologies alone, but in understanding how these approaches collectively define an engineering design landscape, where system architecture, process control, and decision-making frameworks determine overall performance. Figure 11 synthesis this landscape by mapping the evolution of PV recycling technologies against two critical design dimensions: level of process control and selectivity/precision of material separation.

A clear trend emerges from this representation: PV recycling technologies are evolving from low-control, bulk-processing systems towards highly controlled, precision-driven platforms [4,5]. Mechanical recycling, positioned at the lower end of both control and selectivity, reflects a design philosophy based on robustness and scalability, but limited in its ability to preserve material integrity. Thermal systems occupy an intermediate position, introducing process control through temperature and residence time, yet constrained by energy intensity and material degradation risks. Chemical recycling further advances selectivity and recovery efficiency through reaction engineering and purification processes, but introduces increased system complexity, chemical dependency, and environmental management challenges [36].

Emerging approaches such as HVF [16,17,18] and, more prominently, laser-based technologies, represent a transition towards interface-driven and precision-enabled system design. These technologies are not merely incremental improvements but signal a shift in design paradigm, where the internal structure of PV modules is explicitly considered in the design of the recycling process. In particular, laser-based systems, especially those employing femtosecond pulse regimes, offer the potential for non-thermal, highly selective layer separation, enabling recovery pathways that preserve material quality at a level not achievable with conventional approaches.

The increasing level of process control is closely linked to the integration of advanced sensing, digital control, and adaptive optimization strategies. As illustrated in Figure 11, next-generation recycling systems are expected to incorporate AI-driven control architectures, enabling real-time parameter adjustment, process learning, and performance optimization. This evolution aligns with broader trends in smart manufacturing and Industry 4.0 [57,58,59], where recycling systems are no longer static infrastructures but intelligent, responsive platforms capable of adapting to variability in input materials and operating conditions.

Despite the clear advantages of laser-based PV recycling, it is important to recognize that this technology remains within a developing design space, requiring further research, validation, and industrial scaling. Key challenges include the optimization of laser–material interaction mechanisms for different PV module types, the development of cost-effective and energy-efficient laser systems, and the integration of laser processing within existing recycling infrastructures. Additionally, the transition from laboratory or pilot-scale demonstrations to industrial-scale deployment necessitates advances in system throughput, reliability, and economic feasibility.

From a methodological standpoint, the future of PV recycling lies in the development of hybrid and integrated system architectures, where multiple technologies are combined in a complementary manner. Rather than viewing mechanical, thermal, chemical, and laser-based processes as competing solutions, they should be considered as modular components within a unified design framework, each contributing specific functionalities such as pre-conditioning, delamination, purification, or precision separation. This system-level perspective enables more flexible and robust recycling infrastructures capable of handling diverse PV technologies and evolving waste streams.

Importantly, the transition towards next-generation recycling systems requires coordinated efforts across research, industry, and policy domains. Increased investment in research and development is essential to advance laser-based and AI-enabled recycling technologies from conceptual frameworks to deployable solutions. At the same time, industry engagement is critical for validating system designs under real-world conditions and for establishing economically viable business models. Policy frameworks must also evolve to support innovation, standardization, and the adoption of advanced recycling technologies within circular economic strategies.

3.2. Techno-Economic Considerations of PV Recycling Systems

The economic viability of PV recycling systems remains one of the most critical barriers to their large-scale deployment. While significant progress has been made in developing efficient material recovery technologies, techno-economic analyses consistently show that profitability is highly sensitive to system configuration, processing scale, material recovery rates, and external policy conditions.

Table 1. Summary of techno-economic studies [60,61,62,63,64] on PV recycling systems.

Ref./Year	Recycling Method	Key Economic Findings
[60]/2019	Mechanical recycling in an existing laminated-glass recycling facility versus hybrid full-recovery recycling (FRELP)	Neither recycling route was economically profitable under the case assumptions, although recycling cost could be as low as USD 0.03/kg. The study argues that a dedicated PV recycling plant only becomes relevant as waste flows approach ~8000 t/yr.
[61]/2020	Hybrid overall recovery process with collection, transport, disassembly, glass stripping/grinding, heat treatment, and chemical treatment	Recovery cost was USD 25.11/kW, benefit USD 25.68/kW, and net benefit USD 0.57/kW. Reported net present value= USD 21.14 million and benefit–cost ratio= 1.023. On a mass basis, annual unit cost and benefit were USD 334.83/t and USD 342.37/t.
[62]/2021	Hybrid/advanced: organic-solvent delamination followed by downstream thermal and leaching steps	Net cost was USD 29.00/module at laboratory scale and USD 3.30/module for the optimized high-throughput case. The authors conclude that complete material recovery is unlikely to be profitable under median assumptions.
[63]/2023	Plant-level recycling business-case model; route is not the paper’s main comparison variable	For a 3000 t/yr recycling plant, profitability is not verified in the absence of an avoided landfill cost.
[64]/2025	Comparative closed-loop scenarios: full recovery (R1), aluminum + glass recovery (R2), and aluminum-only recovery (R3)	R1 had the best economics with return on investment (ROI) = 52.17%. R2 achieved ROI = 39.53% with an initial investment 47.1% lower than R1. R3 performed poorly with ROI = −31.00%. Environmentally, normalized benefits were 2.98 for R1 and 2.73 for R2; R1 also reduced toxic impacts by 35%.

summarizes selected studies that evaluate the economic performance of PV recycling systems across different technological pathways and operational scales.

A key insight emerging from these studies is that many existing recycling approaches struggle to achieve economic profitability under current market conditions. For instance, both conventional mechanical recycling and hybrid full-recovery processes have been shown to operate at low or negative profit margins, particularly when material recovery value is insufficient to offset processing, transportation, and capital costs [60]. Similarly, plant-level analyses indicate that recycling facilities operating at moderate scales (e.g., ~3000 t/year) are unlikely to be economically viable without additional revenue streams, such as avoided landfill costs or policy incentives. These findings highlight the fundamental challenge of PV recycling: the intrinsic material value of conventional crystalline silicon (c-Si) modules is relatively low compared to the cost of complex separation processes.

Despite these limitations, several studies demonstrate that economic viability can be achieved under specific conditions. Hybrid recycling approaches that combine mechanical, thermal, and chemical processes show improved performance due to enhanced material recovery and value extraction. For example, integrated recovery systems have reported positive net present value and benefit–cost ratios slightly above unity under optimized conditions, particularly when high-value materials such as silver and silicon are efficiently recovered [61]. Furthermore, process optimization and scaling can significantly reduce unit costs, as evidenced by reductions from laboratory-scale costs (~USD 29/module) to high-throughput scenarios (~USD 3.30/module) [62]. These results suggest that economies of scale, process integration, and improved recovery efficiency are key enablers of economically sustainable PV recycling infrastructures.

Another important consideration is the trade-off between recovery completeness and economic performance. While full material recovery pathways (e.g., closed-loop recycling scenarios) can achieve higher environmental benefits and long-term resource sustainability, they often require higher capital investment and process complexity. As shown in Table 1, full recovery systems can achieve strong returns on investment under favorable conditions, but simplified recovery strategies (e.g., focusing on aluminum and glass) may offer lower upfront costs and reduced technical complexity [64]. This highlights a fundamental design trade-off: maximizing material recovery does not always correspond to optimal economic performance, and system design must balance recovery efficiency with cost-effectiveness.

In addition to these techno-economic considerations, the rapid evolution of PV technologies introduces new challenges for recycling system design. While most existing studies focus on conventional crystalline silicon (c-Si) modules [4,7,8,35], emerging technologies such as thin-film (e.g., cadmium telluride (CdTe) [65,66], copper indium gallium selenide (CIGS) [67]), heterojunction (HJT) [68], and tandem or perovskite-based modules [69,70] present significantly different material compositions, layer structures, and degradation behaviors. These variations directly impact recycling strategies, as they require different processing conditions, separation techniques, and material recovery pathways. For example, thin-film modules [65,66,67] involve critical materials such as indium, gallium, and cadmium, which require specialized chemical recovery processes, while next-generation modules may incorporate novel encapsulants or multi-layer architectures that are not compatible with existing recycling infrastructures.

From a system-level design perspective, this increasing diversity in PV module technologies reinforces the need for adaptable, modular, and technology-agnostic recycling systems. Future infrastructures must be capable of handling heterogeneous waste streams, dynamically adjusting processing parameters, and integrating multiple recycling pathways within a unified framework. In this context, advanced approaches such as laser-based processing and AI-driven control systems offer significant potential, as they enable selective, flexible, and data-driven processing tailored to different module types. However, their economic viability remains to be fully demonstrated, particularly at industrial scales.

Overall, the techno-economic evidence indicates that PV recycling is not solely a technological challenge, but a complex systems problem involving trade-offs between cost, recovery efficiency, scalability, and adaptability. Achieving economically viable recycling systems will require not only process optimization, but also supportive policy frameworks, standardization of module design, and the development of integrated infrastructures capable of evolving alongside PV technologies.

4. Conclusions

This paper has presented a system-level engineering design perspective on EoL PV recycling, moving beyond conventional process-based analyses towards a decision-oriented framework that integrates technology selection, system architecture, and operational trade-offs. By analyzing mechanical, thermal, chemical, and laser-based recycling pathways within a unified design space, the study demonstrates that the effectiveness of PV recycling is not determined by individual processes alone, but by how these processes are configured, controlled, and integrated within scalable infrastructures. A key finding is that PV recycling technologies are undergoing a transition from bulk, low-selectivity processing towards precision-driven, highly controlled systems, where material recovery quality, energy efficiency, and environmental performance are intrinsically linked to system design decisions.

From this perspective, several key design insights emerge. Mechanical-based systems provide a robust and scalable foundation for PV recycling infrastructure, particularly suited for high-throughput pre-processing, although their limited selectivity necessitates integration with downstream processes. Thermal-based systems enable effective encapsulant removal through controlled heat transfer but require careful optimization of operating conditions to balance energy consumption and material preservation. Chemical-based systems offer high-purity material recovery, yet introduce complexity in process integration, reagent management, and environmental control. Laser-based systems represent a next-generation paradigm, enabling precise, non-thermal, and interface-selective material separation, with strong potential for integration with digital and AI-driven control frameworks.

Despite these advances, no single technology provides a complete solution, reinforcing the need for hybrid and modular system architectures that combine the strengths of multiple approaches. Importantly, the results of this study highlight that PV recycling is not solely a technological challenge, but a multi-dimensional systems problem involving economic viability, infrastructure scalability, and regulatory alignment. As demonstrated by techno-economic evidence, the profitability of PV recycling remains highly sensitive to processing scales, material recovery rates, and policy support, indicating that technical innovation alone is insufficient to ensure widespread deployment.

In this context, standardization and policy frameworks will play a critical role in shaping the future of PV recycling systems. The development of standardized module designs, recycling protocols, and performance metrics can significantly improve process efficiency and system interoperability. In parallel, extended producer responsibility (EPR) policies and regulatory mechanisms will be essential to incentivize recycling, internalize end-of-life costs, and support the economic viability of recycling infrastructures. Infrastructure readiness is equally important, requiring the development of regionally distributed, scalable recycling facilities capable of handling increasing PV waste volumes while adapting to diverse module technologies.

The rapid evolution of PV technologies further adds complexity to recycling system design. Emerging module types, including thin-film, heterojunction, and next-generation multi-layer architectures, introduce new material compositions and processing challenges that are not fully addressed by existing recycling approaches. This reinforces the need for flexible, adaptable, and technology-agnostic recycling systems capable of accommodating heterogeneous waste streams and evolving material characteristics.

From a future research perspective, several priorities can be identified. First, there is a need for the development of standardized system-level design methodologies that integrate technical, economic, and environmental performance metrics. Second, further work is required to scale advanced recycling technologies, particularly laser-based and AI-enabled systems, from laboratory and pilot-scale demonstrations to industrial deployment, addressing challenges related to cost, throughput, and reliability. Third, the integration of digitalization, sensing, and data-driven control strategies represents a key opportunity for enabling intelligent, adaptive recycling infrastructures. Finally, greater emphasis is needed on techno-economic modeling, lifecycle assessment, and policy-driven system design to ensure that future PV recycling solutions are not only technically effective, but also economically viable and aligned with circular economy objectives.