The objective of this work is to suggest and share the initial results of technologies for recycling EOL c-Si PV panels developed in our laboratories. In this work, we present initial results with two technologies for recycling EOL c-Si PV modules; one each for open-ended and closed-ended recycling approaches as developed on a laboratory scale. For open ended recycling approach, we develop a process of manufacturing FeSi from EOL c-Si PV panels and scrap steel. This is a novel process which does not involve any reducing agents to produce FeSi. It utilizes Si from the EOL PV panels and clean scrap iron to produce FeSi using a simple induction furnace. This eliminates the use of any reducing agents. Since this can be produced in an induction furnace, the only energy input required is in terms of electricity, which can be generated using renewable energy sources. No further sources of heating are necessary. For a closed-end recycling process, an energy-efficient electrohydraulic fragmentation process was developed for delaminating PV modules, which enables the near-complete separation and recovery of the different components of PV modules. In this work, we have shown the compatibility of the EHF process with the crushing process, which is widely used in industry for several recycling applications. We have shown that the EHF process is capable of handling crushed modules, which makes it feasible to be integrated into existing waste handling systems with crushing units to enable handling EOL PV modules.

This work focuses on technology and the engineering development of the processes. In this work, no attempts have been made to assess the economic feasibility or scalability of the process, as the process is at a developmental stage. At this stage, the data collected is insufficient to assess any environmental impact. The authors are in the process of collecting more data from the experimental process to be able to perform a thorough environmental impact assessment, which shall be addressed in future work. Further, no attempts have been made to assess the relationship with the existing or future policies, as it is beyond the scope and expertise of the authors. In this work, the authors have attempted to present technical aspects of the recycling process, which has been developed in a laboratory environment. Both these processes are compared with the current state-of-the-art in terms of energy use and toxic/hazardous products created as a result of the process. Further, a succinct review of the state-of-the-art in the recovery of silver and silicon is also presented. Finally, the inferences are drawn, and the conclusion is presented.

FeSi was prepared using an induction furnace. In this work, FESi45 was prepared, which means that for 100gm of the FeSi45, Si is approximately 45% by mass while the remaining is iron (Fe). Discarded and damaged solar PV panels were collected from a commercial supplier. The solar PV panels were cleaned with water and dried. The aluminium frames and the external electrical connections of the panels were removed mechanically. The solar panels were crushed using a twin-blade mechanical crusher. The crushing was conducted in multiple passes to obtain the desired particle size of 1-3 mm. Between each pass of the crushing process, the glass, silicon, and polymer pieces that were successfully separated were removed manually. The process was repeated until enough silicon pieces were obtained. Two types of silicon pieces were obtained – those which were stuck to the polyethylene film used as the backsheet and those which were completely removed from the polyethylene layer. This was done by a simple sieving process using a sieve of 1 mm opening, as the polymer silicon pieces were all larger than 1 mm. Silicon powder obtained after the sieving process ranged from 0.1-0.8 mm.

The Scrap iron was collected from the discarded materials in the lab (such as stirrers, steel wires, etc). The pieces were washed in warm (≈50℃) soapy water to remove any traces of oil, debris, and organic and inorganic residues on the surface. The rust on the samples was removed using commercial rust-removing spray and scrubbing with a metal brush. The cleaned samples were washed again in warm soapy water to remove the chemicals and dried by placing them in an oven at 150 ℃ for 20 min. The cleaned and dried scrap steel was cut into smaller pieces (≈20-30mm) and prepared for melting. The total mass of the sample prepared was kept constant at 100g. For all samples, the amount of Fe taken was 55g, while the remaining 45g included either the silicon pieces or the powder obtained after the crushing process. The amount of iron required for preparing the sample was measured and placed in the alumina crucible. The alumina crucible was placed inside a larger graphite crucible. The crucibles were covered with an alumina lid with an opening in the centre through which a thermocouple could be inserted to record the temperature. Both crucibles were placed in a cylindrical induction furnace. After the iron melted, Si pieces/powder were added to the crucible. The contents were stirred (intermittently) with the help of a clean quartz tube to check for complete dissolution. After the complete dissolution of the Si in Fe, the furnace was turned off. The sample was left in the crucible, which was covered with the alumina lid, and the sample was allowed to cool down naturally to room temperature. After the sample and the crucible had cooled down, the alumina crucible was broken to retrieve the sample. The samples were cut and embedded in conductive carbon resin, and subsequently, metallographic cross-sections were prepared from the embedded samples by grinding using different grades of sandpaper and polishing with diamond suspension.

For the work reported here, the pieces of modules obtained after crushing were sorted manually. The crushed pieces (with polymer and glass) with a size exceeding 5 mm were selected for processing using shock wave fragmentation for further separation into individual components. The pieces were placed in the process chamber of 5L volume. Deionized water was used as the fluid medium. The voltage input to the electrode was 50 kV while the processing duration was 240s. The EHF process exploits the differences in the mechanical properties of the materials in a PV panel. A high voltage pulse is applied to a fluid in an insulated container in which a solid is immersed. The arcing between the electrodes generates a shockwave which travels through the fluid and interacts with the solids. The interaction between the pressure wave front in the liquid and the solid causes fractures at the weak points between the interfaces of dissimilar materials, resulting in crushing and separation of the materials (Akimoto et al., 2018).

The metallographic FeSi prepared using the silicon recovered from the panels was observed with a scanning electron microscope (SEM). The composition of the distinct phases was analysed using energy dispersive spectroscopy (EDS) integrated with the SEM. FeSi prepared using the silicon pieces stuck with the polymer sheet are denoted as FeSi-pc, and those prepared with the Si powder are denoted as FeSi-po. Figure 5 shows the SEM image and the elemental maps obtained by EDS for the FeSi-pc samples. The polymer sheets used in PV modules are usually Polyethylene Terephthalate (PET) and Ethyl Vinyl Acetate (EVA), as mentioned earlier. Both are polymers involving C, H and O (Królikowski et al., 2024). Therefore, the combustion products generated due to their combustion would be carbon dioxide and water vapour. Some carbon is also expected to be incorporated in the samples. This could be observed in the elemental maps in Figure 5. The FeSi comprised a silicon-rich matrix with a composition of Si ranging between 42-45% (atomic) and a composition of Fe between 48-52% (atomic). The Fe-rich dendrites present in the matrix, on the other hand, had Fe in the range of 60-65% while Si varied between 30-33%. A comparison with the Fe-Si binary phase diagram and experimental phase analysis ((Han et al., 2022); (Kubaschewski & Okamoto, 1993)) reveals the presence of FeSi (Si-rich) and Fe2Si (Fe-rich) phases. The composition of the two phases of FeSi determined by EDS closely corresponds to the stoichiometric composition of the phases expected to be present in FeSi45. The overall percentage of Al in the samples ranged from 2.5-3.5% (atomic). The aluminium is expected to come from the metal contacts on the silicon solar cells, as well as the interconnection wires used to connect the solar cells in a module (Zarmai et al., 2015).

Figure 6 shows the SEM image and the elemental maps obtained by EDS for the FeSi-po samples. In this case, since the polymer pieces were absent, carbon could not be found (reliably) in the samples. However, in this case, Ag was present in the FeSi45 samples prepared. While crushing, most of the metal contacts on the solar cells, which are composed of Al and Ag, are expected to form fine particles under the mechanical stress. Hence, the percentage of metal fraction in the silicon powder obtained after the crushing process would be slightly higher than that found on the silicon fractions still stuck to the polymer pieces. The presence of Fe2Si dendrites in the FeSi matrix was clearly visible, as in the case of FeSi-pc samples. Additionally, Ag could be seen scattered in the microstructure. Since the solid solubility of Ag in Fe and Si is extremely low (Rollert et al., 1987) (Wriedt et al., 1973), Ag is expected to precipitate during cooling and distribute throughout the microstructure. The percentage of Ag in the samples was found to range between 0.1%-0.3% (atomic). The percentage of Al in these samples was found to be between 5-7.5% atomic. Correspondingly, the overall percentage of Si was slightly lower in these samples than that in the FeSi-pc samples. The overall percentages in terms of mass for different constituents for both FeSi-pc and FeSi-po samples obtained from EDS measurements are shown in Table 1. The composition of the commercially purchased FeSi45 is also shown alongside for comparison. There was a loss of 1-3% wt. in the mass of the FeSi product as compared to the total mass of the raw materials used. This can be attributed to the loss due to natural oxidation, loss of volatile compounds, and the mechanical loss while recovering the sample (some part of the sample sticking to the crucible). Table 1 shows that Al in the FeSi prepared with pieces is similar to that present in the commercial FeSi. The overall impurity content in the FeSi produced using recycled Si is less than that present in the commercial FeSi. This further supports the suitability of using recycled Si for producing FeSi.

After the EHF treatment, while most of the glass and silicon were separated from the polymer pieces, the polymer pieces were not completely clean. However, it is known that the degree of separation of the glass and silicon is also dependent on the various process parameters, such as process duration, feed volume, pulse power, among others (Akimoto et al., 2018) (Song et al., 2020) (Zhao et al., 2020). Further optimization of the process parameters could lead to a higher degree of separation and subsequent recovery of the silicon, polymer, and glass. Figure 7 shows the crushed pieces before and after undergoing the EHF treatment.

The powder obtained after the treatment is mostly comprised of glass with a small amount of Si and metal particles. The separation of silicon and glass from the polymer pieces can be explained by the operating principle of the EHF process. The process is based on the difference in the mechanical properties of the materials when subjected to mechanical stress. Since glass is amorphous and brittle, it is easily broken into tiny pieces and separated from the underlying polymer layer. Further, the glass is the thickest layer in the sandwich. The glass thickness is usually between 3 – 5mm. In comparison, both polymers and the Si wafers used for making the solar cells are just a few hundred microns thick. Hence, the impact of the mechanical force is greatest on the glass, and it is easily separated from the underlying polymer sheet. Further, it was seen that the last layer of silicon particles sticking to the polymer layers was not a continuous layer of Si, but rather tiny particles of size less than 100µm. In this form, the particles are discontinuous and less constrained. Therefore, the impact of the pulse on them is further minimized, as they can move with the polymer layer as it deforms under the impulse. Nevertheless, as mentioned earlier, optimization of the process parameters could further help in the higher recovery of the particles after the EHF treatment. Hence, with this treatment, it is possible to retrieve the polymer layers in whole, while recovering silicon (along with the Ag and Al) powder and glass particles. In several test runs conducted, more than 99% of the material was recovered. Since the process uses only water as the medium and the process occurs at room temperature, no toxic gases or effluents are produced. Since water is used as a non-consumable medium, the additional water consumption is also almost negligible. Hence, using the EHF process provides an alternative pathway for recovering all the components of EOL c-Si PV panels.Figure 8 and Figure 9 show the SEM images of the coarse and the fine powders obtained after the EHF processing of the EOL modules.

Electrical current is extracted from silicon solar cells using grid-patterned contacts printed on the solar cells. These metal contacts are typically made of silver paste, along with small quantities of some other proprietary metals. The quantity of silver in the panel is almost negligible in terms of weight (~0.05%); however, the silver accounts for ≈47% of the value of the recoverable materials ((Source Title, 2016); (Chen et al., 2024)). Due to the recent technological advances, PV production is gradually shifting from Passivated Emitter and Rear Cell (PERC) to newer technologies like Tunnel Oxide Passivated Contact (TOPCon) and Heterojunction Technology (HJT). These technologies use more silver in each solar cell, with TOPCon and HJT utilising at least 1.3 times and 1.6 times more silver than PERC, respectively. The World Silver Survey 2023 by The Silver Institute projects the silver consumption in PV panels to increase by 4%, while production is forecasted to increase by only 2%. If the trends remain steady, the PV industry could use up to 98% of the global silver reserves in 2050 ((Survey, 2023)). Therefore, effective recovery of silver from EOL PV modules is crucial to the economic sustainability of the entire recycling process. Recovered silver could also help to offset the production costs of new panels, as well as meet the growing demand for silver. The initial efforts in PV recycling focused on high-volume recovery of glass, aluminium, and metallurgical grade silicon, as these made up over 80% of module mass, were simpler to separate, and the process was cost-effective. Furthermore, recovery of intact solar cells for reuse in module production was prioritised, as the price of PV panels was driven by the cost of silicon wafers ((Task et al., 2018)). Consequently, silver was discarded while recovering silicon by etching the solar cells in sodium hydroxide, as the process was not economically viable, despite the high value of silver.

In the early 2000s, the first attempts were made to recover the silver using hydrometallurgical processes. Nitric acid was used to leach silver from the recovered solar cells. Electrolysis and metal replacement techniques were later employed to recover silver from the precipitated salts from the nitric acid (Deng et al., 2022). The process was 98% efficient in recovering silver from the solar cells. Other methods have been developed in recent years with similar or improved process efficiencies. A 98% recovery rate has also been achieved using a combined hydrometallurgical and electrochemical approach. In this process, silver is leached and then subjected to electrodeposition-redox replacement (EDRR) reaction to recover pure silver. This process minimizes chemical use, thus offering high efficiency and reduced environmental damage (Russo et al., 2024). In the newly developed laser debonding process, silver electrodes are removed using a laser. This method is unique in its ability to selectively recover silver while minimizing the damage to the silicon wafers. Using lasers results in the generation of silver nanoparticles, which can be readily supplied to various industries. Machine learning techniques have been used to optimize laser processing and increase automation for industrial applications, reducing both cost and energy consumption (Khetri & Gupta, 2024). Improving the process efficiency while simultaneously reducing the environmental footprint of the recycling processes is the requirement of a successful and industrially scalable process (Gajare et al., 2025) (Qi et al., 2025) (Zheng et al., 2025). Iron and aluminium chloride in brine solutions have been used to recover up to 95% of silver in under 10 minutes. This process offers the advantages of low cost, low toxicity, and scalability compared to conventional acid-based recovery techniques (Zante et al., 2022). Ag from the PV panels has also been recovered using biological methods ((Pang et al., 2025)).

While recent advances have made the extraction of silver more efficient and environmentally friendly, challenges still persist. Low concentration of silver in the solar cells is one of the crucial factors which determines the economic feasibility of the process. The process of extracting silver from the panels could be expensive due to the complex chemical processes or specialized equipment. As mentioned earlier, the metal contacts often include other metals, such as cadmium, lead, and copper alongside silver. Since these metals have similar chemical properties, the leaching and separation process becomes complicated (Rout et al., 2025) (Russo et al., 2024). One of the biggest technological challenges is recovering silver selectively without affecting silicon and other valuable materials or contaminants. To achieve this goal, the traditional hydrometallurgical techniques need to improve, while simultaneously novel and sustainable methods such as laser debonding, directional solidification and electrochemical recovery need to be developed further ((Li et al., 2025); (Yue et al., 2025)). Additionally, the economic viability of the recovery process remains a challenge for scaling up the technology, which is being exacerbated due to the decreasing silver content in modules.

Silicon recovered from end-of-life Si PV panels has been used to manufacture new silicon solar cells. Crushing of the panels and separating the constituents can yield metallurgical grade Silicon ((Komoto et al., 2018); (Latunussa et al., 2016); (Tao et al., 2020)), which is valued around $2-3/kg depending on the region (I.M.A.R.C., 2024). The higher cost of solar-grade silicon, which is valued between $6-9/kg (Bellini, 2024-04-16), could provide motivation for its production from EOL PV panels. Successful demonstrations of closed-loop recycling of Si have been done (Tao et al., 2020). Recycled silicon from broken solar cells and wafer production has been used to fabricate ingots and subsequently solar cells (Derbouz Draoua et al., 2017). The solar cells made from recycled Si achieved an efficiency of 18.1% while those made from virgin Si exhibited efficiencies of 18.5%. Solar cells were prepared from recycled Si with efficiencies exceeding 20%. For this purpose, the Si was obtained after chemical etching (Palitzsch et al., 2020). Researchers have demonstrated the effectiveness of the etching process in removing metal contamination from silicon ((Huang et al., 2017); (Park et al., 2016); (Park & Park, 2014)). Among the earliest attempt of recovering silicon, researchers used thermal delamination and chemical etching using a combination of HCl, HF, and NaOH to recover 62% of the Si of 8N quality from the EOL PV panels (Wang et al., 2012). Using a slightly different chemicals, such as Hydrofluoric Acid (HF), Nitric Acid (HNO3), Sulfuric Acid (H2SO4), phosphoric acid (H3PO4) and acetic acid (CH3COOH), researchers recovered 79-86% of 5N silicon, using chemical delamination process to remove the glass and the polymers (Kang et al., 2012). Mini-modules were fabricated, and the glass and the EVA layers were removed using thermal delamination (Park et al., 2016). HNO3 and potassium hydroxide (KOH) were used to recover 90% of the silicon. The solar cells prepared from these reclaimed wafers achieved ≈90% of the initial efficiency (Park et al., 2016). HNO3, H3PO4, and KOH have also been used to remove metal and recover 80-90% of the silicon ((Eshraghi et al., 2020); (Huang et al., 2017); (Jung et al., 2016); (Latunussa et al., 2016); (Latunussa et al., 2016)). Solar cells that have not been incorporated in a panel could also be effectively recycled to retrieve ≈ 99% of the silicon (Yousef et al., 2019). Centrifugal separation, microfiltration, and ultrasonic treatment have been used to separate and purify the recycled Si. While recycling Si from EOL modules is a complicated process, there is underlying interest in the research community, as it has been established that silicon recovered from EOL PV panels could be reused for fabricating new solar cells((Lee et al., 2024); (Ramírez-Cantero et al., 2025); (Sah et al., 2023); (Tembo & Subramanian, 2023)).

Al is among the most common impurities in the FeSi alloys. Commercially produced ferrosilicon usually contains between 0.5-2% of Al as an impurity ((Tangstad, 2013); (Tomé-Torquemada et al., 2017)). However, since Al is used as an electrical contact in most electronic devices, due to its excellent electrical conductivity, less weight, and not easily diffusing into Silicon below 300 ℃ ((Kim et al., 2016); (Krause et al., 2002); (McCaldin & Sankur, 1971)). While this work shows the feasibility of preparing FeSi from the recycled Si, the impact of the impurities in the FeSi on the downstream applications needs to be assessed ((Tomé-Torquemada et al., 2017); (Wijk & Brabie, 1996)). Presence of Al in FeSi is not considered to be an issue, as there is a market for FeSiAl specifically in casting and metallurgical industries (Arunkumar et al., 2025) (Jochymczyk et al., 2025) (Zhang et al., 2023). The impact of Ag in the downstream applications needs to be understood in order to assess the viability of using FeSi prepared from recycled Si. Nevertheless, the percentage of Ag in FeSi is ≈ 0.1% wt., and with any further downstream use, its concentration would get even further diluted, and hence, Ag may not pose a grave concern for such applications. For example, such recycled ferrosilicon could be used for the oxidation of steels, and the mechanical properties of such steels could be analysed to assess the impact of the impurities in the FeSi on the properties of the final product. However, assessing the impact of the final product is out of the scope of this work and will be considered in future work.

Similarly, the products obtained after the EHF recycling are found to have cross-contamination. For example, some pieces of Si were found in the glass pieces and vice versa. Some silicon and glass were also found sticking to the polymer surface. However, all these impurities and cross-contamination can be removed using different chemical processes ((Ramírez-Cantero et al., 2025)). Pieces of polymer and Si can remain attached to the glass pieces after EHF processing. A combination of organic chemical and water treatment can remove the polymer particles easily. Si content in the glass cullet is estimated to be less than 0.001% wt. Silicon removal can be done using chemicals that selectively etch Si without affecting glass, such as sodium hypochlorite (NaOCl) or potassium hydroxide (KOH) (Basu et al., 2013) (Divan et al., 1999) (Wind et al., 2002). The composition of the fine powder would dictate the design of the separation process. For the samples prepared in this work, the Si content was higher than that of the glass. The glass was dissolved in HF to retrieve Si ((Padhamnath et al., 2025)). HF also helps in removing the ARC coating on the solar cells ((Brunet et al., 2017); (Jeon et al., 2006); (Knotter & Denteneer, 2001)). Finally, the fine powder fraction comprising Si, Ag, Al, and some amount of glass is highly valuable, especially due to the presence of Ag from solar cells. The Ag in the mixture can be recovered by treating it with HNO3, which will dissolve the silver. The dissolved Ag can be recovered from the acid solution by treating it with other chemicals or using electrolysis ((Oliveira et al., 2020); (Dias et al., 2016); (Li et al., 2024); (Yiwei et al., 2007)). The glass and Si left behind can be separated by dissolving the glass in HF.

EHF recycling could enable the recycling of the polymer used in the PV panels, which helps towards achieving 1000% recycling. By a careful optimization of the process parameters, the amount of Si sticking to the surface could be minimized. Further chemical treatment (with KOH and HNO3) can clean the polymer pieces of any remaining silicon and metal particles. Several specialized processes have been developed for recycling such polymers (Królikowski et al., 2024) (Sinha et al., 2010).

Recycling of EOL PV panels is still in its infancy and is generating huge interest among researchers and technologists alike. For example, in open-ended recycling of PV panels, the panels are crushed, and the glass recovered is used to manufacture fibreglass(Duflou et al., 2018) (Feih et al., 2011) (Scelsi et al., 2011), construction of pavements (Emersleben & Meyer, 2012) or for fabricating other construction components (Mohajerani et al., 2017) (Ogundairo et al., 2019) (Robert et al., 2021). However, these are low-end uses of the valuable material in PV panels and do not justify the economics for large-scale implementation. Recently, researchers tried to use the EOL PV panels along with red mud (waste from the aluminium industry) to produce ferrosilicon (Blaesing et al., 2024). They devised a reduction process using coal and argued that the greenhouse gas emissions from the production of Si were mitigated. However, this was an experimental process, and such endeavours have not seen large-scale commercial applications. FeSi, using the method proposed in this work, can be produced without requiring any complicated process or equipment, and without the release of greenhouse gases. Hence, open-ended recycling of PV panels to produce commercially important products would help in the commercial feasibility of the process and enable large-scale adoption of the technology.

Disassembly, delamination, material sorting and material extraction are the four process steps common to all recycling processes designed to extract valuable materials from the end-of-life PV panels. Each of these steps could further comprise single or multiple process steps (Deng et al., 2022) (Divya et al., 2023). Recycling the external wiring (copper) and the aluminium frames is the easiest (Einhaus et al., 2018). In some instances, commercial recycling of PV panels has been reported to include only these steps, while the remaining portions are discarded (Deng et al., 2022). The most valuable recyclable component in a PV panel is undoubtedly Ag, followed by Silicon. They are usually recovered by etching them in chemicals and later precipitating the metal out of the chemicals ((Oliveira et al., 2020); (Dias et al., 2016); (Tembo & Subramanian, 2023)). The amount of polymer used in a PV panel depends on its design. These polymers could include Ethylene-vinyl acetate (EVA), Polyethylene terephthalate (PET), and polyvinylidene difluoride (PVDF). However, owing to the complex and hazardous recovery process and negligible commercial value, these polymers are almost never recycled ((Achilias & Karayannidis, 2004); (Deng et al., 2022)(Deng et al., 2022); (Divya et al., 2023); (Sinha et al., 2010)).

As mentioned earlier, delamination of the PV panels is among the most crucial steps in recycling EOL PV modules. Delamination is usually achieved by chemical, mechanical, thermal processes, or a combination of processes such as thermos-mechanical or thermo-chemical. In thermal delamination, the PV panels are heated to ≈550℃ to decompose the cross-linked polymers in the PV panels, such as Ethyl Vinyl Acetate (EVA), polyethylene terephthalate (PET) or Polyvinylidene fluoride (PVDF) (Dobra et al., 2022). The polymer decomposition allows for the easy separation and subsequent recovery of the glass, the interconnecting metallic ribbons, and the solar cells ((Fiandra et al., 2019); (Fiandra et al., 2019)(Fiandra et al., 2019); (Lee et al., 2018); (Park & Park, 2014)). However, the heating process is energy-intensive. Polymer decomposition is often associated with the generation of toxic gases. Scrubbing and treatment of the flue gases make the process expensive to implement ((Deng et al., 2021); (Lunardi et al., 2018); (Tammaro et al., 2015), (Tammaro et al., 2016)). In chemical delamination, the modules (crushed or whole) are immersed in inorganic or organic chemicals, with or without heating and mechanical stirring. The chemicals weaken the cross-linked polymers, separating the modules and their components. The chemicals used in such processes are extremely hazardous and require long processing times, sometimes extending more than 10 days (Deng et al., 2022) (Divya et al., 2023) (Lunardi et al., 2018). Researchers have combined chemical treatment with microwaves ((Pang et al., 2021)), ultrasonic waves ((Kim & Lee, 2012)) or supercritical carbon dioxide (Lovato et al., 2021) to shorten the process durations. In all these cases, it was difficult to achieve complete separation of EVA and PET/PVDF. Some researchers employed a second process step (pyrolysis or glycolysis) ((Xu et al., 2021)). Furthermore, disposal of such large quantities of organic chemicals could be environmentally challenging. Mechanical fragmentation techniques are the most widely reported and used approach for delamination (Komoto et al., 2018) (Libby et al., 2018). Mechanical approaches such as shredding, crushing, milling, and grinding have been used for the fragmentation of PV panels (Dias et al., 2018) (Pagnanelli et al., 2016). After these processes, some physical separation methods are employed which can separate the glass, polymers, and the silicon combined with metals (Azeumo et al., 2019) (Klejnowska et al., 2024) (Libby et al., 2018) (Martínez et al., 2024). However, such processes result in the separation of glass, which is the main product obtained in such processes. The polymer is often pyrolyzed or burned to generate heat. Mechanical recycling of PV modules using crushing and shredding is the most widely used technology to handle PV waste due to the low cost. However, such processes create a lot of dust and noise and need active dust and noise suppression systems.

The electrohydraulic delamination process provides flexible processing of the end-of-life c-Si PV panels. Different types of PV panels (Glass-glass, glass-backsheet, Glass-free) can be delaminated with the EHF process. The EHF process can be used if the panels are cut or crushed. However, to maintain uniformity in the process, different panel types should not be mixed in one feed. Through process optimization high high-throughput and high-quality materials could be obtained. The capability of the EHF process in enabling complete recyclability of EOL PV panels and recovery of high-quality materials, including polymers, was demonstrated in this work. The materials could easily be separated employing a simple mechanical sieving process. However, the process has immense capabilities, and we have just scratched the surface. Ongoing and future research would aim at optimizing the process to improve the quality of the output materials. Efforts are underway to develop a multistage processing sequence, including automatic and continuous separation of the materials. Investigations into implementing density-based separation of materials, recovering and purification of high-quality silicon and metals (especially Ag) would further increase the effectiveness and efficiency of the EHF process.

The EHF process effectively delaminates the EOL PV modules, providing an alternative to the thermal or chemical delamination processes. The HDF process delaminates c-Si PV panels easily and quickly, without the generation of toxic or hazardous by-products. It also allows for the complete recovery and recycling of different components of the EOL PV panel. These benefits align with the current standards of the EU WEEE directive ((Deng et al., 2021); (CENELEC, 2012-08); (Padoan et al., 2019); (Sica et al., 2018)). The process can be adapted to process different types of PV modules undergoing varied pretreatment processes (crushing, cutting). The only working medium required is non-potable water which is not consumed in the process and can be recycled easily. It needs only electricity to operate, which can be generated by renewable resources. It does not lead to the emission of any hazardous or toxic by-products. This points towards the easy scalability of the technology for commercial applications. A concept of the industrial machine using EHF applications could involve a dryer and sieve-based separators after the EHF process steps, allowing for automation and easy control of the process. However, some cross-contamination of the materials obtained after processing could not be ruled out, and probable steps for remediation have been discussed earlier. A simple mechanical filtration of the processed material leads to the distinct fractions. The large glass pieces can be separated from the finer particles and can be immediately sent for cleaning and recycling. The coarse fraction may contain glass + silicon (from solar cells), and further processing could be decided based on the target material and the composition of the fraction. Similarly, the fraction containing fine powder mostly comprises Si and metal, but can also contain a varying amount of fine glass powder. Density-based medium separation could be used to separate the materials with dissimilar densities(Akimoto et al., 2018) . Ongoing and future efforts would optimize the process parameters to minimize cross-contamination and continuous material separation and recovery using an automated sieving process. Improving the metals recovery yield, purification of Si and metals, and estimating the environmental impact of the process have also been left for future work.

The production of FeSi using recycled Si is an effective way to obtain valuable FeSi product from the waste and discarded PV modules. This is a novel process which does not involve any reducing agents to produce FeSi. It utilizes Si from the EOL PV panels and clean scrap iron to produce FeSi using a simple induction furnace. This eliminates the use of any reducing agents. Further, since this can be produced in an induction furnace, the only energy input required is in terms of electricity, which can be generated using renewable energy sources. No further sources of heating are necessary. This aligns with the sustainable development goal of Responsible consumption and production ((Economic et al., 2015)). Since induction furnaces are already used for recycling metal wastes (especially steel), the FeSi production using recycled steel and EOL PV panels can easily be scaled up for commercial applications. Further, it was found that the FeSi produced from recycled Si has overall lower impurities than those present in the commercial FeSi. The recycled Si obtained from EOL panels contain Al (1-3% wt.), which is an advantage, and FeSiAl is a valuable material used in the metallurgy industry. Al is among the most common impurities in the FeSi alloys. Commercially produced ferrosilicon usually contains between 0.5-2% of Al as impurity, which supports the deoxidation and alloying properties ((Tangstad, 2013); (Tomé-Torquemada et al., 2017)). Further, researchers have tried to produce FeSi using Al-rich clay(Amanov et al., 2017) (Shevko et al., 2016). Using this process, FeSiAl could be produced easily without any additional source of Al. There could be some additional impurities associated with Si recovered from EOL PV panels; however, these impurities are in extremely small quantities (<0.1% wt.) and hence are not expected to impact the quality of the final product achieved.

Not applicable

The author(s) declare that there is no competing interest.