End-of-life photovoltaic modules: A systematic quantitative literature review

Resources, Conservation & Recycling 146 (2019) 1–16

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End-of-life photovoltaic modules: A systematic quantitative literature review

T

Sajjad Mahmoudia, Nazmul Hudaa, , Zahraossadat Alavia, Md Tasbirul Islama, Masud Behniab ⁎

a b

School of Engineering, Macquarie University, North Ryde, NSW 2109, Australia Macquarie Graduate School of Management, Macquarie University, North Ryde, NSW 2109, Australia

ARTICLE INFO

ABSTRACT

Keywords: EoL PV modules Recycling Recovery PV waste management Forecasting Reverse logistics

PV modules which are installed worldwide have a defined lifetime for useful service after which the panels become End-of-Life (EoL) products. An enormous amount of obsolete solar PV modules will be added to the waste stream in the near future. Hence, the EoL photovoltaic waste stream could cause an appalling problem in the future if a holistic management strategy is not considered. Despite the vast research on photovoltaic technology, little is known about the perspective of how the EoL PV modules will be handled. The current study systematically investigates global research on EoL PV modules to identify gaps for further exploration. The review reveals that most of the research concentrates on the recovery and recycling of PV panels. Also, the vast majority of the research is mostly carried out in laboratory-scale. The geographical distribution of the studies was concentrated on 15 countries including the USA, Italy, and Taiwan, the latter of which has produced the most publications. Life-cycle-assessment and reverse logistics (RL) are two critical aspects of PV waste management and have only recently received attention from researchers, with 11 and six papers respectively. There are still many countries which have not attempted to forecast their EoL solar-panel waste stream and develop recycling infrastructure. Based on review findings, the future research must be focused on forecasting the PV waste streams, development of recycling technologies, reverse logistics and the policies of individual PV consumer countries. Finally, this study develops a foundation for future research on Photovoltaic waste management to build upon.

1. Introduction The generation of clean and environment-friendly electricity without the depletion of natural resources is a valuable advantage of photovoltaic (PV) modules (Chen and Pang, 2010; Solangi, Islam et al. 2011; Celik et al., 2018). Production and installation of PV cells have seen significant growth all around the world (Xu et al., 2018a). This rapid growth is limited by resource shortages which necessitates a proactive plan for EoL management of PV modules (Choi and Fthenakis, 2010a,b, Goe and Gaustad, 2016). While there have been numerous efforts in managing and recycling other ends of life electronic items around the globe (Islam and Huda, 2018; Dias et al., 2018a,b), recycling the waste PV modules has always been overlooked. Hence, in order to properly manage the massive and complex waste flows generated by the installation of PV panels, various plans and schemes are required for different PV technologies (Choi and Fthenakis, 2010a,b). Some countries, especially Italy, are attempting to solve the technological, economic, and environmental issues involved in the disposal of

⁎

recent PV module waste. They achieve this with a sustainable genuine progress plan from a technical and socio-environmental perspective (Malandrino et al., 2017). Hence, quantifying the treatment and management of used solar panels at the end of their operational life is becoming more and more dominant. Consequently, the development of PV module recycling as a multidisciplinary field of study needs a sustainable strategy for the disposal of obsolete photovoltaic panels (Cucchiella et al., 2015). To control and evaluate the EoL PV modules, looking at the available technologies can be helpful. Although more than 80% of the global PV modules consist of crystalline silicon (c-Si), there are various other categories of solar cells which should also be carefully looked at to develop an innovative approach for EoL recycling. In Table 1, the range of the PV technologies and their specification is depicted including PV area, power, weight and efficiency. This information is necessary for waste projection, economic analysis and life cycle assessment.

Corresponding author. E-mail address: [email protected] (N. Huda).

https://doi.org/10.1016/j.resconrec.2019.03.018 Received 11 October 2018; Received in revised form 4 March 2019; Accepted 15 March 2019 0921-3449/ © 2019 Elsevier B.V. All rights reserved.

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Table 1 PV classification based on the technologies (Paiano, 2015) and PV specifications (Dominguez and Geyer, 2017). PV generation

Type of PV modules per technology

First generation (c-Si)

a) b) c) a) b) c) d)

Second generation(thin-film)

Third generation: Concentrative Photovoltaics CPV and emerging technologies

a) b) c) d)

Mono crystalline Polycrystalline c) Ribbon sheets Amorphous Silicon (a-Si) Cadmium Telluride (CdTe) Multi-junction cells (a-Si-μc Si) d) Copper indium gallium diselenide (CIGS), Copper indium diselenide (CIS) CPV Dye-sensitised solar cells c)Organic solar cells d) Hybrid cells

Datasets

PV modules

Area [m2]

Power [Wp]

Weight [kg]

Efficiency [%]

Average weight (kg/Wp)

Ecoinvent 3.3 Perseidsolar First Sunergy Ecoinvent 3.3 Sharp Sunelec Kaneka Ecoinvent 3.3 First Solar GE Ecoinvent 3.3 Xsunx Stion tsmc

c-Si

1.46 1.69 1.59 2.3 1.4 1.42 1.22 0.72 0.72 0.72 0.72 1.6 1.09 1.09

224 225 230 128 130 100 110 65 85 78 80 160 135 145

23 25 23 18.86 26 24 18.3 12 12 13 12.6 28 16.8 17.5

15.3 13.3 14.4 5.6 9.3 7 9 9 11.8 10.8 11 10 12.3 13.3

0.103 0.111 0.100 0.147 0.200 0.240 0.166 0.185 0.141 0.167 0.157 0175 0.013 0121

a-Si

CdTe CIGS

1.1. Photovoltaic waste treatment

PV modules was presumed three decades on average for both scenarios with a probability of 99.99% loss at 40 years after installation (IRENA: Stephanie Weckend, 2016). The amount of total obsolete PV panels will surge substantially over the next years which necessitates a longwinded plan.

A waste hierarchy prioritizes the treatment of wastes according to their impacts on endangering human health and harming the environment ;in particular, without risk to water, air, soil, plants or animals, without causing a nuisance through noise or odors, and without adversely affecting the countryside or places of special interest (Commission, 2008). Hence, Fig. 1 illustrates the waste management hierarchy from the most to least preferable treatment procedures developed by the EU Member States (Commission, 2008). With an average lifetime of 20 to 30 years for photovoltaic panels, a massive volume of PV panel waste will emerge shortly (Kim and Jeong, 2016; McDonald and Pearce, 2010). Fig. 2 depicts the current and future cumulative amount of EoL PV panel waste from two different scenarios including the early-loss scenario, the regular-loss scenario and the trend of cumulative installation of PV module from 2016 to 2050 (IRENA: Stephanie Weckend, 2016). The average panel lifetime for the

1.2. Aims and significance of the current review The idea of carrying out a systematic quantitative review on EoL photovoltaic scrap was supported by studying two papers in the field of EoL management of PV modules. (Malandrino et al., 2017) published a review paper and highlighted the concerns connected to the end-of-life management of the PV modules in Italy descriptively from the technoeconomic and socio-environmental perspectives. Furthermore, (Tao and Yu, 2015) performed a comprehensive review on the current feasible recycling methods and technologies for the treatment of the EoL PV modules and depicted the associated environmental benefit and the economic feasibility of them in the recycling business. Both reviews emphasized the severity of an environmental load of PV waste from improper recycling strategies and inappropriate policies and regulation. It was pinpointed that it is necessary to encourage manufacturers and recyclers to consider the potential benefits of recycling, this includes, an efficient collection network, which can provide economic viability. Furthermore, they have a responsibility regarding the treatment of obsolete solar cells in the entire energy industry. Table 2 provides a critical analysis of the existing review papers in the area of EoL PV modules. Although the previous review studies investigated and discussed some aspects of the EoL PV modules, no systematic quantitative reviews have been performed regarding the current status of global performance on the managing of PV modules at the end of their useful life. This review is quantitative as it quantifies where the research is in terms of the geographical location of the research, scale and type of treatments, the trend of the studies in a global scale, the emerging research direction, highlights the gaps and many other aspects.

Fig. 1. Hierarchy of Waste legislation and policy of the EU Member States (Commission, 2008). 2

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Fig. 2. Estimated cumulative global waste volumes (million t) of end-of-life PV panels based on regular-loss and, Early-loss scenarios, IRENA (2016) and IEA (2014) (IRENA: Stephanie Weckend, 2016).

2. Methodology

The current review assesses the emerging application of PV waste materials in different industries, and the trend of the research in the categories of, treatment procedure, environmental impact, life cycle assessment, policy and management, and reverse logistics throughout the years recorded in the literature and elucidation implemented. To support the awareness of the potential risk derived from the EoL PV panels, it is aimed to examine the available literature based on PV modules’ EoL from a different perspective in this current study. This research systematically evaluates and unifies the existent literature focusing on the EoL PV treatment and management with a goal to outline what is clear about the management of PV modules EoL worldwide, and what needs to be investigated further. The quantitative literature review was employed regarding exploring the research projects, the type of PV technology, research method, the journals in which the papers were published in and the reported treatment methods. The scale and geographical distribution of the research are also considered. By doing so, this review paper counts the different aspects of the EoL photovoltaic management sectors in the world to light up the main initiative undertaken globally for photovoltaic waste management. The significance of this review is quadruple. First, even though the awareness for management of PV disposal has increased (Fthenakis, 2000; Cucchiella et al., 2015; Paiano, 2015; Dominguez and Geyer, 2017; Shin et al., 2017; Smith et al., 2017), there is a lack of systematic quantitative analysis to create a better balance and structure for the future research path. This study, hence, scrutinizes the locations, subjects, and variables to find the gaps in the current understanding of EoL PV waste. Also, the overall development and landscape of research in regulation, recycling, economics, logistics and environmental impacts of PV scrap is disclosed. Second, the extended review advances current understanding of the treatment scale and the types of PV technologies evaluated as well as a synergy between the two in the field of PV waste. Third, as a consequence of growing interest in using PV technologies as alternative electricity supply, providing a clear map regarding the estimation of EoL material compositions of PV module for every PV consumer country might be helpful. Thereby, this review also measures the global research on the forecasting of PV waste amounts in every country so that the gaps and opportunities for research are screened. Fourth, it is an undeniable fact that the life cycle of PV cells includes environmental impacts. However, only a few life cycle assessment (LCA) studies have been carried out on PV scrap at this stage. Hence, this review explores how countries have evaluated the environmental impacts of their EoL PV modules so that any gaps can be found for further research. As supplementary information to detect future and recent recovery and recycling methods, all relevant patents registered on the online patent databases were collected and categorized quantitatively. As a result, it was attempted to suggest new opportunities for research on the treatment of PV modules at the end of their useful life. Finally, according to issues detected in the review, an agenda for the future is proposed.

2.1. Systematic quantitative literature review There are numerous varieties of review methods; such as critical review, literature review, meta-analysis, systematic search and review (Grant and Booth, 2009). Among the review methods, the systematic quantitative literature review is systematic and comprehensive in condensing and portraying a large body of research. The quantitative study is objective-oriented and includes statistical analysis (Grant and Booth, 2009). This method can also be employed for trans-disciplinary research and provides an outstanding database to indicate geographic, scalar, theoretical, and methodological gaps in the literature (Pickering and Byrne, 2014). In addition, because quantitative literature review discloses what is clear according to the specific research questions by counting and charting, this method is very useful in encapsulating the landscape and borders of knowledge and revealing insight into what yet should be known (Pickering et al., 2015). The enthusiasm of the current investigation lies in mapping and screening the perspective, pattern, and status of the discoveries in photovoltaic end-of-life management fields. It covers the policy and regulations, reverse logistics, environmental and health manners, life cycle assessment, treatment methods, geographical and regional manner, material flow analysis, risk assessment, and economics. To do so, a systematic quantitative approach is esteemed as a very suitable tool. The review process exhibited in Fig. 3 shows the systematic process of this review method which is updatable and works well for emerging areas as undertaken in this study. 2.2. The systematic review process This study is based on the systematic quantitative literature review process to map and review EoL PV waste management. Hence, a review protocol regarding search terms, databases and screening criteria are accomplished to monitor and conduct the literature review objectives elucidated in the preceding sections. This approach persists on a systematic basis for the literature search, data extraction, and hierarchy of the relative importance of the collected information and research gaps. A flowchart shown in Fig. 41 is developed to demonstrate the process of registering the identified papers into the database. Research published related to photovoltaic waste is obtained using online reference-retrieval databases including: Web of science and Science direct, with search keywords photovoltaic waste, PV waste, end-of-life PV, waste Photovoltaic, end-of-life photovoltaic, waste photovoltaic module, photovoltaic reverse logistic, solar panel waste, photovoltaic recycling, photovoltaic scrap, PV recycling, photovoltaic 1 PRISMA stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

3

4

Recycling paths for thin-film

Policies and Sustainable Management of Solar Panel End-of-Life

(Malandrino et al., 2017)

(Marwede et al., 2013)

Management of end-of-life photovoltaic panels

(Sica et al., 2017)

Recycling pathways and technologies of PV modules

Solar-panel recycling technologies

(Xu et al., 2018a,b,b)

(Tao and Yu 2015)

Topic

Author/ Year

Table 2 Summary of the critical analysis of the previous review articles.

Renewable Energy

Solar Energy Materials & Solar Cells

Sustainability

Renewable and Sustainable Energy Reviews

Waste Management

Name of Journal

Worldwide

Worldwide

Europe/Italy

Worldwide

Worldwide

Scope

of solar panels and related waste generation • Production for solar-panel recycling • Techniques for solar-panel recycling • Policies of producer responsibility • Expansion to further develop an economically feasible and non-toxic technology. • Need promotion of productive paradigms for a ‘closed cycle’ economy based on the enhancement of • The resource efficiency and the reduction of waste. the most critical elements, potential opportunities, and limitations for enhancing recovery and • Highlighting recycling rates. of a financial framework necessary to overcome financial barriers and to ensure the support of all • Creation stakeholders by developing a collaborative approach of innovative pathways of waste management and reverse Logistics • Developing development and diffusion of innovative organisational and technological methods for waste • The management associated with the disposal and/or recycling of EoL PV modules • Issues elements and potential opportunities deriving from the technological, managerial, and • Critical organizational options available to elevate recovery and recycling rates of PV panels and economic aspects associated with the end-of-life management of the modules • Technical importance of awareness and responsibility of the players on the circular economy of obsolete • The photovoltaic panels necessitation of perspective of environmental improvement • The of propitious actions by enterprises operating in the PV sector for development of advanced integration • Lack systems in the management of PV modules absence of adequate practices examined and implemented for the disposal and recycling of photovoltaic • The modules EoL management of the PV supply chain through the involvement and awareness on the part of the • Sustainable actors of rendering the End-of-Life treatment of PV waste for achieving higher efficiency a circular • Necessitation economy perspective of currently commercially available PV modules • Overview of three recycling pathways including manufacturing waste recycling, disposed module • Evaluation remanufacturing and recycling from perspectives of close-loop life cycle of the advantages and drawbacks each pathway and their technologies • Illustration need for the enhancement of recycling process efficiency, reduction in process complexity, • Substantial energy requirements, and use of chemicals implication and legislation for encouraging of producer responsibility in the entire energy industry • Policy of appropriate collection network of PV modules EoL for the elevation of the economic viability • Developing in recycling business. of recycling concepts for thin-film chalcogenide PV modules EoL • Overview of the upsides and downsides of the feasible mechanical or chemical processes • Summarizing up proper collection and recycling systems by responsibility PV producers to avoid environmental • Set harm • Necessitation of adopting appropriate policies

●Impact coverage / ■future research direction

S. Mahmoudi, et al.

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Fig. 3. The steps of the systematic quantitative literature review (Pickering and Byrne, 2014).

Fig. 4. A PRISMA diagram adopted from (Moher, Liberati et al. 2009).

disposal PV panel recovery. The keywords are selected by reviewing various review papers in the field of photovoltaic technology and electronic waste. A certain amount of trial and error is used in a mix of databases to identify the initial best keywords. It ensures the selection of the search terms are comprehensive and covers all major scientific papers related to the research questions of this review. Following this, one or more search terms in combination with others and a range of synonyms are

employed by contacting different experts in this field. Finally, the keywords of the frequently cited papers are used to cross-check if the search terms are sufficiently comprehensive. This study did not consider any non-English journals. To protect and guarantee the grade and standard of review, and to allow integration of the information notably, only those original research papers on photovoltaics waste that had been peer-reviewed and published in academic journals are quantified in this review. Therefore, 5

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according to this search protocol, the original papers which our search terms were found in their title, abstract and keywords entered into the database without a timeframe. To make the database more comprehensive and extensive, papers found by examining the reference lists of the articles are also added to the database. The information recorded for each paper in the database includes author, year of publication, the country where research is done, the journal published in, the method employed, citation, and journal impact factor. Afterward, they are categorized according to the following indicators of regions, PV technology, research methodology, scale, treatment procedure, environmental impact, life cycle analysis, policy and management, reverse logistics. In order to record the detected data in a categorized database, a table of the summary is developed. Then, bibliographic details and a summary of the eligible papers are tabulated both quantitatively and narratively. The scale of the studies is classified as laboratory/small scale, medium scale, and large scale according to the size of the geographical region and the volume of the wastes investigated by scholars. Details of the location were recorded based on the continent and countries. Typologies of solar modules were categorized into three main groups including first, second and third generation based on their technologies and counted as they are employed in the studies. Global warming, human health and toxicity, ecosystem, climate change, and resources depletion are sorted and reviewed in the form of the main subheading of life cycle analysis (environmental impact). The types of treatment consist of incineration, recycling, and landfilling are also quantified and evaluated. The methodology used in the papers are categorized based on analytical, experimental and simulation. The policy and management status of EoL PV cells is organized as a risk assessment, policy and regulation, economics and finance, forecasting and material flow analysis. As a separate and essential heading, reverse logistics is studied and quantified based on the three subsidiary sections collecting, network design, and sorting/processing. In each part, the authors, journals and geographical information of the research are also recorded. Then, applying a descriptive method, the database was analyzed to identify any patterns and direction in the reviewed papers.

Table 4 Number of published studies (1981–2018) that studied PV EoL.

3. Review findings and results In this section, some general statistics are tabulated in Table 3 regarding the four major disciplines considered in the literature over the years. All the subjects have seen rapid development and dramatic attention by scholars over the last five years. In total, the field of treatment procedure had the highest proliferation with 28 papers from 2013 to 2017 followed by policy and management with 13 articles. The attention on the topic of LCA (environmental impact), on the other hand, has considerably increased by 12 papers, while reverse logistics had only a marginal surge, which suggests that this subject might get more attention shortly. The quantitative data extracted from selected studies are depicted in Table 4. As can be seen, 70 journal articles surveyed the photovoltaic module EoL from different scientific aspects and were categorized based on nine main indicators according to the objectives of this review. Regarding the geographical classification section, Europe achieved

19931997

19982002

20032007

20082012

20132017

Treatment procedure LCA (Environmental impacts) Reverse logistics Policy and management Total

0 0

2 0

2 0

9 3

28 12

0 0 0

0 1 3

0 0 2

1 6 20

5 13 65

Total

All studies Region America Europe Asia Oceania Africa PV technology 1st generation 2nd generation 3rd generation Types of research analytical simulation experimental Scale laboratory scale medium scale large scale Treatment procedure recovery recycling reusing landfilling Environmental Impact global warming human health and toxicity ecosystem climate change resources depletion life cycle assessment incineration recycling landfilling Policy and management risk assessment policy and regulation economics and finance forecasting waste stream material flow analysis Reverse logistics collecting network design sorting/processing

70

%

18 28 24 0 0

25.7 40.0 34.3 0.0 0.0

38 37 1

50.0 48.7 1.3

20 14 41

26.7 18.7 54.7

47 5 14

71.2 7.6 21.2

30 13 0 3

65.2 28.3 0.0 6.5

5 7 5 5 6

17.9 25.0 17.9 17.9 21.4

3 10 6

15.8 52.6 31.6

3 4 12 5 7

9.7 12.9 38.7 16.1 22.6

4 4 4

33.3 33.3 33.3

the first rank regarding researching PV module EoL with 28 (39.4%) studies while Asia and USA conducted 24 (33.8%) and 19 (26.8%) and ranked in the second and third positions respectively from 1981 to 2018. Surprisingly, there was no recorded publication at the international level in Oceania and Africa. Over half (41 papers) employed experimental methods, 24 performed analytical study, and 14 used simulation software to study various aspects of photovoltaic waste treatment. Most of the studies worked on the 1st and 2nd generation of the photovoltaic technologies with 37 and 38 papers respectively, as they were the most common types of PV cells installed worldwide during the last 20 years. In contrast, the third generation of solar cells with only one paper has not got enough incentive yet for scientists to evaluate as e-waste from different aspects of the study. Research scale is defined into three classes. The first category is the studies established in a pilot-scale like an evaluation of only one PV module or part of it. The medium scale refers to the level of research which covers the amount of PV modules installed in a city or part of a country. The third category includes the studies at the level of a country or broader. Assessing the scales of the studies, the laboratory-scale was more addressed by scientists (71% of the total investigations). However, the large-scale studies have been less considered by 14 papers (21.2%) followed by five articles (7.6%) as medium scale. In the category of the treatment procedure, recovery by 65.2% (30

Table 3 Literature profiles by discipline and publication years till 2018. Discipline

Category

6

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papers) achieved the first position in the list, followed by 28.3% (13 papers) on the recycling sector and only 6.5% (3 papers) assessed landfilling and no papers on the reusing approach. The distribution of the research regarding five dominant scenarios of environmental impacts was highly diverse. Human health and toxicity (25%) was the most researched impact, followed by resources depletion (21.4%), global warming and ecosystem (both 17.9%). Across these studies, LCA of PV EoL was investigated in 11 papers in such a way that the LCA of PV waste recycling was analyzed in 10 papers (52.6%) followed by landfilling with 6 papers (31.6%), and incineration had the minimal interest among researchers with only 3 papers (15.8%). Further, policy and management were other categories of the end of the treatment of the PV cells. The results illustrated that economics and finance was the most notable factor represented with 12 papers (38.7%). The next rank was achieved by material flow analysis with 7 papers (22.6%), while there were a few papers in the area of risk assessment, policy and regulation, and forecasting with 3, 4 and 5 papers respectively. Reverse logistics were divided into the three sub-groups, collecting, sort-test/inspection, and processing so that the papers were recorded according to these indicators. Thus, there was a harmony between the indicators with 4 (33.3%) papers each.

aforementioned countries with 7, 6 and 5 papers respectively, while the rest of the countries in the list had only a few publications in this field. Five important indicators in the area of waste management, recycling, life cycle assessment, reverse logistics, economic analysis, and forecasting, were chosen in order to observe the number of field researchers in these areas and find potential research opportunities for more exploration and assessment. In fact, it is clear that finding an optimal and comprehensive solution for the treatment and management of PV waste at the end of its useful life totally depends on conducting a vast research, gathering and organizing information to get a broad perspective regarding the best method of waste collection, transportation, recycling method and economic feasibility (Fthenakis, 2000; Cyrs et al., 2014; Dominguez and Geyer, 2017; Zeng et al., 2017). However, there is a lack of well-defined schemes for the treatment of the obsolete photovoltaic panels in many countries. Consequently, it is suspected that the PV waste flows will be dealt like the other industrial wastes. Table 5 illustrates that Taiwan had the highest contribution in the recycling of the EoL PV modules with 8 papers, while the other investigations in the recycling section were quite fragmented to various countries, the USA, Korea, Netherlands and China with only 1–2 papers each. Besides, the results show that Italy was significantly purposeful and intentional in the evaluation of the environmental impact of PV waste treatment methods using LCA with 4 papers followed by USA, Germany, and China, published 3, 2 and 1 papers respectively. It is noted that even though the development of a closed-loop supply chain and reverse logistics is accounted as a critical sector in the field of electronic waste management (Dias et al., 2016), the reverse logistics section is one of the intact research directions in the field of EoL PV waste management with only 6 papers. USA and Taiwan are the only two countries in the world who performed some investigations on RL, with 4 and 2 papers respectively.

3.1. Global distribution of research on EoL PV cells The cumulative global installed capacity of PV cells reached 222 GW at the end of 2015 (IRENA: Stephanie Weckend, 2016). Although PV technology as a global commodity possesses economic profitability and provides environmentally friendly electricity, it also has a specific operational lifetime and then needs decommissioning (IRENA: Stephanie Weckend, 2016). The data reported in Fig. 5 depicts the worldwide PV capacity until the end of 2015. PV technologies have spread to almost every part of the world and are developing day-by-day. Hence, providing a sustainable future is essential and needs regulatory frameworks and appropriate policies for end-of-life treatment. In response to this need, it might be useful to have a look at the current global efforts for management of EoL PV wastes. Fig. 6 provides the geographical distribution of the selected papers, focusing on the number of publications in each country. The table is provided in descending order. Although research has been done in 16 countries/locations, most articles were from USA (15), Italy (13) and Taiwan (10). Korea, Germany, and China were the most researched group after the

3.2. Keyword analysis Due to the recent growth of research on EoL PV modules resulting in a large body of literature, it is challenging to perform a broad and comprehensive review manually. Thus, keyword analysis of bibliometric data as an automated and systematic approach efficiently provides detailed information regarding the network of the keywords used in the database and consequently classifies them in different clusters. By creating a bibliometric map, the method of keyword analysis effectively highlights the definite trends, networks between the frequently repeated terms and the direction of research which then allows for finding

Fig. 5. Global overview of photovoltaic energy installed capacity (IEA, 2018). 7

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Fig. 6. The distribution of studies on EoL PV waste in the world.

decreased to 116 by applying a minimum occurrence of 2 in the database. Hence, the outcome of the keyword analysis of title and abstracts of the EoL PV cells publications are shown in Fig. 7. The size of the label and its circle shows the weight of the item. If the weight of an item surges, then the size of the label, as well as the related circle, will increase and vice versa. Hence, the keyword’s size represents frequent application and utility of the keywords among the publications. The other important factor is the distance between the items so that the higher the number of co-occurrences the smaller the distance between the two items. Having examined the scientific landscape map, it can be obviously expressed that the distance between the clusters varies according to the type of items in each cluster. In general, the distance between the green and red clusters is the shortest, while the blue cluster is located at a larger inter-cluster distance from the former clusters except for the three items efficiency, waste, and silicon located about the middle of the three clusters. As is clear, the three aforementioned keywords are very common in all the clusters. The efficiency item plays a very important role, not only in the process of the recycling and recovery of EoL PV materials and substances, but also an assessment of the environmental impacts of all EoL PV treatments as well as in the economic and management aspects of this kind of electronic waste. Apparently, waste as a general keyword is logically expected to be situated in the center of the map. More importantly, silicon as the most applied material in the photovoltaic industry shows frequent co-occurrences in the various research approaches of the EoL PV module. The red cluster in the area of PV waste constitutes terms more related to the process of the recovery of photovoltaic waste materials including the mechanical, thermal and chemical treatments as well as the anticipated costs and feasibility of the process from the economic point of view. On the other hand, the green cluster depicts the environmental impacts of the various EoL PV module treatments such as landfilling, recycling and incineration of the PV scrap via different scenarios like global warming, climate change, and energy saving. Besides, forecasting the emerging waste from Eol photovoltaic and the management of the waste in terms of reverse logistics are also the main contents of this cluster. Finally, the blue cluster is the representative of recycling technologies and their economic feasibility in the area of photovoltaic EoL. The items outlined in this cluster emphasize problems such as lowcost procedure, high-efficiency methods, new applications of PV waste

hidden gaps and future opportunities within the field. Therefore, the keywords in the title and abstract of the 70 peerreviewed papers recorded from Web of Science (WoS) source into our systematic review database were evaluated using a free text-mining software known as VOSviewer (Van Eck and Waltman, 2010). The number of terms detected in the selected publications was initially found to be 2858, while filtration had the minimum occurrence number of 2, indicating that the evaluation procedure is able to identify a wide range of terms including the most occurrence keywords and also emerging items in the database. In the final step, a built-in text mining function was applied using the VOSviewer software. It is noted that a thesaurus file as one of the function of VOSviewer was used to omit generic words, some singular, plural, and merged forms of the terms enters to the analysis. In accordance with the co-occurrences of the items, VOSviewer created a co-occurrence map and links between terms so that the detected items were systematically clustered. In fact, co-occurrence is defined as a concept which refers to the words appearing in a single document or the number of publications in which two terms occur together. In the next step, the names of the clusters were manually defined as three colors. Thereby, the detected items in the field of EoL PV modules were presented in a scientific landscape. In this manner, there were three indicators including the clusters’ size, color, and distance which depict the frequency of the items’ co-occurrences, the types of detected items and their relevance respectively. In other words, a short distance between clusters meant that the co-occurrence of the items was more frequent, while the larger gaps represent that they were not very relevant. Table 6 shows a summary of the clusters classifications as well as the relevant topic along with the number of keywords in each cluster. As can be seen the red cluster, with 42 items, is the representative of the recovery process and costs topics and gives the number of detected items in its cluster, whereas the green cluster is responsible for PV waste management and environmental impacts with 37 keywords. It is followed by 37 items for the blue cluster which depicts the contribution of the items in the recycling and economic feasibility sector. Considering the title and abstract of the 70 journal papers, a total of 2858 items were detected without a time limitation filter. In order to cover a wide range of items from the oldest to the latest items in the form of scientific landscape map, the number of eligible items was 8

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Conversely, the recyclers were more concerned about finding new applications for the recovered materials rather than on the evaluation of environmental impacts of the reprocessing of original materials. It has to be highlighted that there is a clear opportunity for scholars to employ LCA into the process of recycling to find the potential impacts of the reprocessing of the recovered materials on the environment under different scenarios. Looking at the items appearing in the scientific landscape map of EoL photovoltaic modules from the bibliometric analysis of the title and abstracts keywords in the papers between 2012 and 2017, the latest concentration of researchers is revealed and also gaps are identified in this emerging topic (Fig. 8). This map can present how the keywords appear in the field of PV waste treatment chronologically and what are the emerging keywords and directions on this controversial topic. As is evident, there are several major keywords including recycling, waste, PV module, recovery, energy, silicon, efficiency, glass, cost, environmental impact, disposal and metal which were much more frequently used. This is a very great clarification about the main concerns of the researchers in this field so far. On the other hand, taking a closer look at the map, it can be seen that researchers are concentrating on recovery of materials such as silver, aluminum as special metals, cadmium as a hazardous material, and tellurium, gallium as critical materials. There is a wide variety of emerging keywords found in the database. The most recent materials investigated in the recovery section are silver and aluminum. On top of that, keywords such as forecast, cost reduction, and economic feasibility are the newest concerns in PV waste management. Considering the keywords used in the current database, it is clear that reverse logistics, forecasting, and environmental assessment of PV waste at the end of its useful life have not been comprehensively assessed for each country.

Table 5 Geographical research distribution on End of life PV modules. Subject

Number of Publications

Country

PV Technology

Scale

Recycling

13

China Netherlands South Korea South Korea Taiwan Taiwan Taiwan Taiwan Taiwan Taiwan Taiwan Taiwan USA China Germany Germany Italy Italy Italy Italy Spain USA USA USA Taiwan Taiwan USA USA USA USA Netherlands Belgium Canada Germany Italy Italy South Korea USA USA USA USA USA Belgium Germany Italy USA USA

c-si c-si c-si c-si c-si/thin film

Lab Lab Lab Lab Lab Lab Lab Lab Lab Lab Lab Lab – Lab Lab Large – Lab Medium Lab Large Lab Medium Lab Large Large Lab Large Medium Large Lab Large Lab Lab Large Medium Large Large Medium – Large Large Large Large Large Large Large

LCA

11

Reverse Logistics

6

Economic assessment

Forecasting

12

5

thin film c-si/thin film thin film thin film c-si thin film thin film c-si/thin film thin film c-si thin film thin film thin film c-si thin film thin film c-si c-si c-si thin film c-si c-si/thin film thin film c-si c-si/thin film c-si/thin film c-si thin film thin film thin film c-si c-si thin film c-si/thin film thin film c-si/thin film

3.3. Frequency of journals and research areas The frequency of the journals, area, and citations of each paper are further presented in the following tables. Examining the research approaches employed by researchers in different scientific areas can enhance insights toward potential research fields in each scientific direction. In Table 7 the distribution of the papers in the top 5 scientific research subjects is provided using the web-of-science result-analysis option. Currently, the five research directions below include environmental sciences, energy fuels, engineering environmental, materials science multidisciplinary and physics applied, and are the major interesting research directions on the EoL PV waste treatment topic. Table 8 indicates the distribution of the papers in the top 8 journals in the field of EoL photovoltaic waste treatment. Despite the fact that half of the papers (50%) were published in these eight journals (35 papers out of 70), the rest of the studies had a very diverse distribution among the international academic journals because this is an emerging topic which different scientists by various approaches are attempting to present new directions and discoveries in this field.

such as geopolymer, cement, brick, and ceramic. In addition, from the clustering results, it is apparent that the cooccurrences of environmental impact related keywords occur less in the area of recycling technologies and new applications of PV waste materials. In other words, the papers that studied recycling of the EoL PV wastes have not applied life cycle analysis in their investigations. On the other hand, the researchers in the field of PV waste material recovery did not focus on the process which was going to be employed after recovery of the materials to reach the new application.

3.4. Bibliometric details of the papers in EoL PV treatment The process leads us to the final set for review, composed of 70

Table 6 Keyword clustering by Publication title and abstract. z

Research topic

Some of the observed keywords

No. of keywords

Red

Recovery process and costs

42

Green

PV waste management and environmental impacts Recycling technologies and economic feasibility

Waste flow, valuable material, thin film, thermal treatment, recovery, an organic solvent, market share, nitric acid, sulfuric acid, hydrometallurgy, glass, cost, etching process, chemical treatment, mechanical treatment, Economic feasibility, emission, life cycle assessment, environmental impact, landfill, global warming, management, secondary row material, reverse logistics, forecast Silicon, waste, efficiency, geopolymer, cement, pyrolysis, waste glass, hazardous waste, economic benefit, cost reduction,

Blue

9

37 37

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Fig. 7. The scientific landscape of EoL PV panels by publication. Table 8 Top Journals for EoL PV cells research.

Table 7 Publication distribution based on research areas. No. of Pub.

%

Environmental Sciences Energy Fuels Engineering Environmental Materials Science Multidisciplinary Physics Applied

37 29 25 19 16

44.58 34.94 30.12 22.89 19.28

Impact factor

No. of studies

%

Solar Energy Materials & Solar Cells Resources, Conservation and Recycling Waste Management Cleaner Production Energy Policy Hazardous Materials Progress in Photovoltaics: Research and Applications Renewable Energy Total

5.018 5.120 4.723 5.651 4.039 6.434 6.456

8 5 5 4 4 3 3

22.86 14.3 14.3 11.43 11.43 8.6 8,6

4.9 –

3 35

8.6 50

in the last period to 16 and then 19 patents from 2014 to 2016. Hence, it is obvious that the recovery and recycling of EoL PV panels became a major concern for scientists and scholars. In addition, supplementary information on the established patents is available in Appendix A. In Table A1 the patents registered in the area of PV waste recovery and recycling are provided including their patent ID, followed by their title and citations based on their year of publication. It is worth noting that 63 patents were discovered from the Google patent dataset 33 patents for crystalline silicon PV modules and 31 devoted to thin-film modules. The contextual analysis of every patent revealed that there is a huge gap in the environmental assessment of the PV panel recovery and recycling procedures using various LCA scenarios. Also, the recent patents tabulated in Table A1 can be an excellent opportunity for the evaluation of financial profitability of various methods to identify the valuable options for future policy and regulation.

Fig. 8. The scientific landscape of EoL PV panels by the publication from 2012 to 2017 and onwards.

Research subject

Journals

papers from 39 journals. Table 9 summarizes the relevant articles published in the EoL PV module research area. The publications were sub-grouped according to the research title, citations of the article, Author, and finally the year of publication.

4. Discussion and future directions The main findings of the current study are outlined in the following section and, based on the patterns recognized from the review, advice, and tips are remarked for further exploration.

3.5. State-of-the-Art EoL PV patents Fig. 9 depicts that the number of patents in the area of PV waste recovery and recycling increased significantly over the years. It is clear that the trend had two constant parts between 1998 and 2008 and then from 2010 to 2013. Afterward, it rocketed more than four to five times

4.1. Global PV waste projection & infrastructure The global market of the photovoltaic industries indicates that there 10

11

48 49 50 51

39 40 41 42 43 44 45 46 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

End-of-life management and recycling of PV modules, (106), (Fthenakis, 2000) Electrochemical approach for removal, separation and retrieval of CdTe and CdS films from PV module waste, (2), Menezes, 2001, (Menezes, 2001) Experimental study on PV module recycling with organic solvent method, (23), (Doi, Tsuda et al. 2001) Pyrolysis of EVA and its application in recycling of photovoltaic modules, (7), (Zeng, Born et al. 2004) Extraction and Separation of Cd and Te from Cadmium Telluride Photovoltaic Manufacturing Scrap, (20), (Fthenakis and Wang, 2006) Large sample activation analysis: Monitoring of photovoltaic module recycling using radio analytical methods, (4), (Segebade, Hedrich et al. 2008) Regulatory policy governing cadmium-telluride photovoltaics: A case study contrasting life cycle management with the precautionary principle, (15), (Sinha, Kriegner et al. 2008) A novel approach for the recycling of thin film photovoltaic modules, (52), Berger, (Berger, Simon et al. 2010) Chemical, thermal and laser progress in recycling of photovoltaic silicon, (5), (Radziemska et al., 2010a,b) Economic Feasibility of Recycling Photovoltaic Modules, (25), (Choi and Fthenakis, 2010a,b) Producer responsibility and recycling solar photovoltaic modules, (66), (McDonald and Pearce, 2010) Experimental validation of crystalline silicon solar cells recycling by thermal and chemical methods, (19), (Klugmann-Radziemska et al., 2010) Chemical treatment of crystalline silicon solar cells as a method of recovering pure silicon from photovoltaic modules, (29), (Radziemska, Ostrowski et al. 2009) Design and Optimization of Photovoltaics Recycling Infrastructure, (16), (Choi and Fthenakis, 2010a,b) Elucidating the effects of solar panel waste glass substitution on the physical and mechanical characteristics of clay bricks, (2), (Lin, Huang et al. 2013) Experimental investigations for recycling of silicon and glass from waste photovoltaic modules, (34), (Kang, Yoo et al. 2012) Future recycling flows of tellurium from cadmium telluride photovoltaic waste, (40), (Marwede and Reller, 2012) Potential Cd emissions from end-of-life CdTe PV, (5), (Raugei, Isasa et al. 2012) Recycling Solar Panel Waste Glass Sintered as Glass-Ceramics, (3), (Lin, Chu et al. 2012) Dissolution of ethylene vinyl acetate in crystalline silicon PV modules using ultrasonic irradiation and organic solvent (4), (Kim and Lee, 2012) Future recycling flows of tellurium from cadmium telluride photovoltaic waste (41), (Marwede and Reller, 2012) Adsorption of toluene on mesoporous materials from waste solar panel as silica source (4), (Ma and Ruan, 2013) An Application of AHP and Sensitivity Analysis for Measuring the Best Strategy of Reverse Logistics: A Case Study of Photovoltaic Industry Chain (4), (Lin and Shiue, 2013) Evaluation of the environmental benefits of new high value process for the management of the end of life of thin film photovoltaic modules (13), (Giacchetta, Leporini et al. 2013) Life cycle analysis of silane recycling in amorphous silicon-based solar photovoltaic manufacturing (19), (Kreiger, Shonnard et al. 2013) Photovoltaic's silica-rich waste sludge as supplementary cementitious material (SCM) (3), (Quercia, van der Putten et al. 2013) Thin-Film Photovoltaic Cells: Long-Term Metal(loid) Leaching at Their End-of-Life (14), (Zimmermann, Schaffer et al. 2013) Utilization of Solar Panel Waste Glass for Metakaolinite-Based Geopolymer Synthesis (4), (Hao et al., 2013) Crystalline silicon photovoltaic recycling planning: macro and micro perspectives (28), (Choi and Fthenakis, 2014) Effects of waste material from solar panels on mechanical properties and durability of cement based materials (0), (Cheng, 2014) Landfill waste and recycling: Use of a screening-level risk assessment tool for end-of-life cadmium telluride (CdTe) thin-film photovoltaic (PV) panels (17), (Cyrs, Avens et al. 2014) Recovering valuable metals from recycled photovoltaic modules (8), (Yi, Kim et al. 2014) Recovery of germanium from waste solar panels using ion-exchange membrane and solvent extraction (4), (Kuroiwa, Ohura et al. 2014) Recycling of Indium from CIGS Photovoltaic Cells: Potential of Combining Acid-Resistant Nano filtration with Liquid − Liquid Extraction (9), (Zimmermann, Niewersch et al. 2014) Recycling of photovoltaic panels by physical operations (19), (Granata, Pagnanelli et al. 2014) Removal of CdTe in acidic media by magnetic ion-exchange resin: A potential recycling methodology for cadmium telluride photovoltaic waste, (3), (Zhang, Dong et al. 2014) Wet etching processes for recycling crystalline silicon solar cells from end-of-life photovoltaic modules, (7), (Park and Park, 2014) Estimation of Life Cycle Material Costs of Cadmium Telluride- and Copper Indium Gallium Diselenide-Photovoltaic Absorber Materials based on Life Cycle Material Flows, (16), (Marwede and Reller, 2014) Constructing a network model to rank the optimal strategy for implementing the sorting process in reverse logistics: case study of photovoltaic industry (4), (Hsueh and Lin, 2015) Effects of sintering temperature on the characteristics of solar panel waste glass in the production of ceramic tiles, (4), (Hsueh and Lin, 2015) Elucidation characteristics of geopolymer with solar panel waste glass, (0), (Hao et al., 2015) End-of-Life of used photovoltaic modules: A financial analysis, (21), (Cucchiella et al., 2015) Evaluating the availability of gallium, indium, and tellurium from recycled photovoltaic modules, (11), (Redlinger, Eggert et al. 2015) Implications for current regulatory waste toxicity characterisation methods from analysing metal and metalloid leaching from photovoltaic modules (1), (Collins and Anctil, 2017) Photovoltaic waste assessment in Italy, (17), (Paiano, 2015) Recovery of valuable materials from end-of-life thin-film photovoltaic panels: environmental impact assessment of different management options (9), (Rocchetti and Beolchini, 2015) Thermal treatment of waste photovoltaic module for recovery and recycling: Experimental assessment of the presence of metals in the gas emissions and in the ashes (5), (Tammaro, Rimauro et al. 2015) An anticipatory approach to quantify energetics of recycling CdTe photovoltaic systems, (2), (Ravikumar, Sinha et al. 2016) Closed-Loop Supply Chain Planning Model for a Photovoltaic System Manufacturer with Internal and External Recycling, (2), (Kim and Jeong, 2016) Estimating direct climate impacts of end-of-life solar photovoltaic recovery, (1), (Goe and Gaustad, 2016) Exploring an Interesting Si Source from Photovoltaic Industry Waste and Engineering It as a Li-Ion Battery High-Capacity Anode, (2), (Huang, Selvaraj et al. 2016)

Title, (citation by web of science), (Authors, Year of Publication)

Table 9 Lists of the 70 studies examining the impacts of the EoL PV panels.

▄

Х Х Х

▄

Х Х □ Х Х

▄

Х

▄

Х

▄

▄

▄

▄

▄

▄

▄

▄

Х

▄

▄

▄

Х □ Х □ Х

▄

▄

Х Х

▄

▄

Х

▄

▄

Х Х

▄

Х □

▄

▄

▄

▄

▄

▄

Treat-ment

Impact coverage

▄

Х Х

▄

Х

Х Х

▄

▄

▄

▄

Х Х Х

▄

Х Х Х Х Х Х Х □ Х □ Х Х □ Х Х Х

▄

Х Х □ Х Х Х

RLb Х Х Х Х Х Х Х Х Х Х Х Х Х

▄

▄

Х

Х

▄

Х Х Х Х Х Х Х Х

▄

Х Х Х Х Х Х Х Х Х

▄

Х Х Х Х Х

▄

Х Х □ Х Х Х Х Х Х Х Х

▄

▄

Х Х

P&Mc Х Х Х Х Х Х

(continued on next page)

Х

▄

Х

▄

Х

▄

Х Х Х Х Х Х Х

Х □ Х Х Х □ Х Х Х Х Х Х Х

▄

▄

Х

▄

Х Х Х

▄

▄

Х Х Х Х Х Х Х Х

▄

LCAa Х Х Х Х Х Х Х

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Х Х Х Х Х

Х Х Х Х Х Х Х ▄

Х

Impact coverage: a = Life Cycle assessment, b = Policy and Management. c = Reverse logistics. Impact coverage: a = Life Cycle assessment, b = Policy and Management. c = Reverse logistics. ▄ = complete coverage; □= partial coverage (not very detailed); Х = no coverage.= complete coverage; □= partial coverage (not very detailed); Х = no coverage.

▄

▄

▄

▄

Х

▄

▄

64 65 66 67 68 69 70

▄

Х Х Х Х

▄

Х

▄

▄

▄

are a rapid internationalization and commoditization of supply chains originating from high deployment rates, growing the capacities of manufacturing and demand. With reference to the IRENA in 2016, the top 10 countries in the world in terms of the number of cumulative installed solar panels were China, Germany, Japan, USA, Italy, UK, Spain, France, India, and Australia. China had the highest amount of installed PV panel with 43 GW, while India and Australia represented the least capacity with 5 GW each. In connection with this development, a massive amount of waste, 78 million tonnes (MT), is predicted from global end of life PV modules by 2050, with China at 20 MT as the greatest producer of PV waste followed by the US 10 MT, Japan 7.5 MT, and India 7.5 MT (IRENA: Stephanie Weckend, 2016). According to the finding of this review, five papers were found which focused on the screening and forecasting of the local end of life PV waste belonging to Belgium, Germany, Italy, and the USA. (Paiano, 2015), (Peeters et al., 2017) claimed that the projection of the potential waste could lead to enhance the correct disposal of hazardous substances as well as the recovery and recycling of the precious materials. By forecasting and quantifying the PV materials for the next century, the economic profitability of the recovery and recycling of the valuable materials such as gallium, indium, and tellurium from PV panels as well as the reusing expenditures of each part were examined. It also assesses how these costs evolve over time (Redlinger et al., 2015). A proper recycling plan and proposing right technology for recovery of valuable metals and appropriate disposal procedure for hazardous metals can be guaranteed by forecasting the amount and kind of metals contained in the photovoltaic waste (Dominguez and Geyer, 2017). Estimation of the amount of waste, the material composition of PV modules at the end of their operational life, the development and the market growth for tellurium metal were assessed (Marwede and Reller, 2012). Finally, the findings confirm that there is a lack of monitoring and reporting systems at the national and regional level to cover the streams of PV waste in each PV consumer country to achieve a holistic decision and better management. The statistical data provided by this system can effectively improve the predictions of the waste stream and lead to better awareness regarding the regulatory framework revision (IRENA: Stephanie Weckend, 2016).

Х Х Х Х Х □ Х

▄

Х

Х Х

Х Х ▄

▄

▄

Х Х

Х Х Х Х Х Х Х

Х

Life Cycle Assessment of an innovative recycling process for crystalline silicon photovoltaic panels, (9), (Latunussa, Ardente et al. 2016) Photovoltaic panel recycling: from type-selective processes to flexible apparatus for simultaneous treatment of different types, (0), (Pagnanelli, Moscardini et al. 2016) Recycling WEEE: Extraction and concentration of silver from waste crystalline silicon photovoltaic modules, (6), (Dias et al., 2016) A method to recycle silicon wafer from end-of-life photovoltaic module and solar panels by using recycled silicon wafers, (3), (Shin, Park et al. 2017) Economic Feasibility for Recycling of Waste Crystalline Silicon Photovoltaic Modules, (0), (D’Adamo et al., 2017) Electrodynamic Eddy Current Separation of End-of-Life PV Materials, (0), (Smith, Nagel et al. 2017) Electrostatic separation for recycling silver, silicon and polyethylene terephthalate from waste photovoltaic cells, (0), (Zhang et al., 2017b) End-of-life treatment of crystalline silicon photovoltaic panels: An emergy-based case study, (1), (Corcelli, Ripa et al. 2017) Environmental impacts of PV technology throughout the life cycle: Importance of the end-of-life management for Si-panels and CdTe panels, (0), (Vellini, Gambini et al. 2017) Environmental influence assessment of China’s multi-crystalline silicon (multi-Si) photovoltaic modules considering recycling process, (2), (Huang, Zhao et al. 2017) Forecasting the composition of emerging waste streams with sensitivity analysis A case study for photovoltaic (PV) panels in Flanders, (1), (Peeters, Altamirano et al. 2017) Photovoltaic Monocrystalline Silicon Waste-Derived Hierarchical Silicon/Flake Graphite/Carbon Composite as Low-Cost and High-Capacity Anode for Lithium-Ion Batteries, (1), (Lu, Ma et al. 2017) Photovoltaic performance of c-Si wafer reclaimed from end-of-life solar cell using various mixing ratios of HF and HNO 3, (0), (Lee et al., 2017) Photovoltaic waste assessment in Mexico, (0), (Dominguez and Geyer, 2017) Physical and chemical treatment of end of life panels: An integrated automatic approach viable for different photovoltaic technologies, (1), (Pagnanelli, Moscardini et al. 2017) Recycling WEEE: Polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules, (2), (Dias, Javimczik et al. 2017) Silicon carbide recovered from photovoltaic industry waste as photocatalysts for hydrogen production, (2), (Zhang et al., 2017a) Toxicity assessment and feasible recycling process for amorphous silicon and CIS waste photovoltaic panels, (1), (Savvilotidou, Antoniou et al. 2017) Waste Photovoltaic Panels for Ultrapure Silicon and Hydrogen through the Low-Temperature Magnesium Silicide, (0), (Dytrych, Bumba et al. 2017) 52 53 54 55 56 57 58 59 60 61 62 63

▄

Impact coverage Title, (citation by web of science), (Authors, Year of Publication)

Table 9 (continued)

▄

Х Х Х Х

▄

Х Х Х Х Х Х Х Х Х Х Х Х

S. Mahmoudi, et al.

4.2. Limitations of EoL PV research field Lack of proper awareness regarding the potential profitability of recycling and the value of the materials which can be extracted from the obsolete PV modules may cause incentive reversal and neglection to recycle (Dominguez and Geyer, 2017). There are only a few papers related to the end-of-life phase of PV mostly since the number of panels reaching the end of their operational life is not reasonable. Meanwhile, there is a lack of data associated with the end-of-life PV modules (Latunussa et al., 2016). One of the objectives of this review was to identify the number of life cycle assessments investigated on EoL photovoltaic modules and the related geographical location. As mentioned earlier in the review finding section, only a few studies were found with the aim of assessing the environmental impacts of the EoL PV panels. According to the present literature, China, Germany, Italy, Spain, and the USA are the five main countries which performed LCA for their PV scrap. It is somewhat surprising that only two studies among the 11 papers dealt with the large scale. It is required to have a number of important details connected to the recovery and recycling of EoL PV materials if it is wished to have a strong LCA and environmental impact assessment with the lowest uncertainty (Berger et al., 2010; Huang et al., 2017; Raugei et al., 2012). Life cycle analysis improves the recovery strategies of EoL PV materials by estimation of the required energy for recovery, recycling and transportation of the PV waste. This results in minimization of energy consumption and development of better infrastructure (Ravikumar et al., 2016). The emission from processing EoL solar panels originates from the transportation infrastructure; its impact on vulnerable populations needs to be evaluated 12

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studies were conducted in Taiwan, with eight papers, and the rest of the studies were held by other countries including South Korea (2 articles), China, USA and Netherlands with only one paper each. These peer-reviewed articles were mostly published recently within the last 10 years. With a comprehensive evaluation of the results, it is apprehended that the recycling applications of the recovered materials from the EoL PV module are very demandable in other industries, for example, for the production of Li-Ion batteries, geopolymers, cement, brick and ceramic, cosmetic and paint making. It illustrates the multiple applications of PV scrap as a valuable kind of waste. The feasibility of using recovered PV waste materials for the manufacturing of new solar panels indicated that fabricated PV modules with recycled wafers had a similar efficiency to that of virgin panels (Shin, Park et al. 2017). Mesoporous silica materials synthesized from waste solar panels had a high performance to absorb the emitted gas from gaseous toluene (Ma and Ruan, 2013). A case study showed that solar panel waste glass could be employed as a raw material for ceramic tile fabrication (Lin, Lee et al. 2015). Photovoltaic waste glass could effectively improve the favorable mechanical characteristics of geopolymers as a partial replacement for metakaolinite (Hao et al., 2015). Thereby, the studies have successfully demonstrated that PV waste can be worth recycling not only for the PV industry but also for other sectors. Also, even though recycling and recovery are intimately connected, it was found in the review that the percentages of the recovery papers to recycling papers were about 43% to 18%. Hence, there is more to be explored regarding the recycling of EoL PV panels. In general, it seems that the research direction in the coming years should tap into the recycling of PV wastes applying industrial approaches to examine other potential applications of EoL PV modules as an electronic waste. The current review reveals that the PV recycling technologies are divided into the delamination process, and material separation and purification (Radziemska et al., 2010a,b, Pagnanelli, Moscardini et al. 2016). There is a range of methods for the delamination process including physical pre-treatment, chemical and thermal treatments and solvent dissolution. The material separation and purification section, on the other hand, is more involved with the chemical treatment (etching), laser surface cleaning, electrodynamic Eddy Current Separation (EECS), electrostatic separation technology, and hydrometallurgical treatment. However, the main challenges to develop and scale up the current PV recycling technologies are the reducing of gas emission and temperature during the delamination process, choosing a proper mixing ratio for etching process, decreasing of using chemicals and chemical wastes production, and achieving high level of purity (Radziemska et al., 2010a,b, Pagnanelli et al., 2016). Furthermore, to grow up the recycling technologies from the pilot level to the industrial scale considerable amount of PV waste is imperative for creating of economic feasibility (Cucchiella et al., 2015). In order to evaluate the waste stream of EoL PV modules and propose appropriate waste management strategies and adequate policies for recycling, it is necessary to provide clear and detailed information of current and future PV technologies (Paiano, 2015). The results of this study indicate that the coverage of the first and second generations of PV in the literature are very similar, with 38 and 37 papers respectively. It is somewhat interesting that only one paper related to the CPV was detected as the third generation of the photovoltaic technologies. A possible explanation for these results may be the lack of adequate data for the different types of the third Solar panel generation. In other words, the third generation of the PV modules are not sufficiently broad and pervasive which could create an incentive for research and exploration, or they are still at the research level. A future study with more focus on the 3rd generation of PV technologies is therefore recommended so that the best recovery and recycling strategies can be investigated and discovered. The environmental impacts of the end of life 3rd PV generation should be evaluated to make a better decision from different aspects. Hence, more research on various types of 3rd and emerging generation of PV technology needs to be undertaken before they are commercialized and spread worldwide.

Fig. 9. Patents trend analysis on the treatment procedures of EoL PV modules.

using LCA (Goe and Gaustad, 2016). Also, human health issues arising from the dispersion of landfilled waste dust requires an imperative environmental impact assessment connected with LCA (Goe and Gaustad, 2016). Quantifying and evaluating the sustainability and environmental performance of the EoL PV panel treatment process can be effectively covered by LCA to identify the critical issues for the environment, and may point to a proper direction of the management of EoL photovoltaic cells (Rocchetti and Beolchini, 2015). LCA of decommisioned solar panels has a decisive role to develop an effective treatment directive and reduce the potential risks such as human health, resource depletion, and global warming. However, LCA of obsolete PV panel has been generally excluded or neglected by the users of the PV panels in different countries owing to the lack of global and local appropriate regulations. Therefore, further investigation and exploration are strongly needed to effectively develop a holistic treatment strategy, depending on the limitations (amount and value) of each country. Additionally, understanding of the reverse logistics comprising collecting, processing and network design of solar modules at the end of their technical life is imperative to develop a sufficient recycling infrastructure from various perspectives including financial and environmental. The lack of a detailed analysis of the reverse logistics for the waste flows associated with the obsolete PV modules is obvious, as there are only six published articles from USA and Taiwan. This represents the importance of original contributions from the other countries to the field of RL. The emissions arising from the transportation of PV waste from installed sites is one of the major environmental problems associated with the RL of the EoL PV modules (Choi and Fthenakis, 2010a,b; Goe and Gaustad, 2016). Incidentally, it is also to be noted that the evaluation of the level of marginal capital cost of each PV tack-back center, the reverse logistics expenses, distance traveled, and the amount of PV waste collected from various locations have a very important role for making economic decisions (Choi and Fthenakis, 2014). It is necessary to provide the best level of economiclogistics planning which will guarantee the environmental viability of the infrastructure management of the PV recycling plans by minimizing the travel distance while maximizing the volume of the collected waste and its delivery to recycling centers. Optimal location of the PV takeback centers needs to be assessed comprehensively (Choi and Fthenakis, 2010a,b). Together, these findings provide a strong insight for future research by PV consumer countries and scholars to set up the efficient infrastructure for managing and recycling of the EoL PV modules. The major aspects which are required to be addressed are the location of network channels, the amount of waste handled by a take-back center, andthe potential problems derived from the reverse logistics supply chain such as collection process and transportation. Since a large amount of PV scrap will be produced shortly, developing a cost-effective recycling methods is required to reduce environmental issues (Menezes, 2001). Based on the review of recycling papers in the literature, 13 journal articles were detected which referred to applications of the recovered PV materials in either the photovoltaic industry or other potential industries. The majority of the 13

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4.3. Management implications

overlooked. In general, notwithstanding these few constraints, this is the first review paper to explore the EoL PV modules literature quantitatively. This review has provided an overview of the research on EoL PV panels all around the world and identified gaps in each field. Therefore, when looking at this review, readers need to take into account the particular research gaps, define the desired research direction, plan to provide the required information and propose the best solution for the short and long-term responses. As a result, the data and knowledge presented in this way could empower the authorities for developing proper recycling strategies.

Because of the precious resources employed in PV technologies and the waste generated at the end of their operational life, a proactive strategy for developing PV recycling infrastructure is necessary (Choi and Fthenakis, 2014). This relies on the estimation of the waste stream, optimization of the reverse logistics system, analysis of the economic viability, and evaluation of the environmental impact. Furthermore, it is opportune to highlight that the inconsistency and unbalance in the research and findings fail to cover all the aforementioned factors in parallel, leading to a negative impact on the whole life cycle of PV cells as a green energy technology. From the literature, in order to guarantee the economic viability and profitability of investment on PV waste, providing a considerable amount of PV waste is necessary (Cucchiella et al., 2015). To do this, a centralized system to monitor the amount of waste globally is highly recommended. Thereby, every country which invests in PV technology as an alternative source of electricity generation might also think about the end of life management of their PV waste as well. However, it is worth noting that the management of EoL PV modules relies on a systematic strategy. It means that different levels of management should be carried out on the agenda covering macroscopic, mesoscopic and microscopic scales of e-waste with more focus on the microscopic scale (Zeng et al., 2017). For managers of EoL PV modules, the most important results of this review are the details of the global research on EoL photovoltaics modules in terms of geographical location, scale, the area of the topic, and distribution of the research chronologically in the PV-consuming countries. Researchers can find the gaps in each sector and try to develop their research for implementing the cycle of PV chain management. In this study, efforts were made to systematically identify what studies have been implemented in a particular part of the world in terms of research contents, scale, type of technology and its treatment method among others. For instance, the projection of the PV waste stream and investigation of reverse logistics are required to be evaluated by every PV consumer country. However, currently only a few countries examined these two aspects of PV waste management. A further important gap appeared in this systematic review is that the cost effective analysis which is a critical factor for encouraging all parties to get involved in the end-of-life treatment of PV panels, which is very little explored in most of the countries. In addition to this, the latest patents about the recycling and recovery procedures of the EoL PV panel were presented so that the researchers can choose from them and employ the LCA to evaluate its environmental impacts. Also, the new applications of the recovered PV materials have been identified using keyword analysis which can provide new opportunities for research and further exploration. Despite the advantages of the systematic review method, it possesses some limitations owing to its intrinsic nature, like being retrospective, observational and selective (Petticrew and Roberts, 2006); this study was not exempt from these limitations. Thus, the number of papers found during the initial search led to a vast collection of papers with a high level of irrelevancy. As a consequence, the search format had to be revised into title, abstract and keywords. Accordingly, studies which did not mention the key items in the segments above may have been overlooked. Notwithstanding these limitations, it was attempted to use various combinations of the keywords to ensure that our search items covered all relevant studies. Also, the reference lists of the observed papers were manually checked to find any missing articles. Finally, it is suggested that a balance between precision and exhaustiveness might be more efficient while doing a systematic quantitative literature review. Additionally, the objective of this review was to cover all research related only to end of life PV panels. Hence, other areas such as PV manufacturing waste were not emphasized. Also, it should be noted that all studies which were not written in English have been

5. Conclusion This paper presents a systematic quantitative review of end-of-life PV panels. The evidence from this study illuminates the overall landscape of research on the dismantled PV panels all around the world covering treatment, policy and management, the projection of PV waste generation, lifecycle analysis, and reverse logistics. It is apparent from the investigation that the treatment procedures, including recycling, recovery, reusing and landfilling had the highest attention among researchers. However, there are still critical challenges to develop and scale up the current PV recycling technologies such as the reducing of gas emission and temperature during the delamination process, choosing a proper mixing ratio for the etching process, decreasing of using chemicals and chemical wastes production, and achieving a high level of purifications. Also, the considerable volume of PV waste is necessary for recycling viability and economic feasibility of PV waste treatment. This study further reveals that there are international fragmental studies regarding research on various aspects of the EoL PV modules. While the sustainable management of obsolete photovoltaic panels would be influenced by the lack of accurate data on the waste flow of each PV consumer country, only about 16% of studies related to specific countries have attempted to estimate their EoL PV waste streams. It shows that more contribution is needed from the other countries to develop accurate data centers for forecasting of the waste flow in addition to designing a proactive strategy. Finally, creating a universal monitoring system which systematically monitors the amount of PV waste and treatments on various scales comprising microscopic, macroscopic and mesoscopic levels can potentially help the decisionmakers, investors and companies to come up with the more reliable solutions and possible management strategies. Acknowledgments The first author acknowledges funding support from Macquarie University under the International Macquarie University Research Training Program scholarship (IMQRTP). Appendix A. Supplementary data Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.resconrec.2019.03. 018. References Berger, W., Simon, F.G., Weimann, K., Alsema, E.A., 2010. A novel approach for the recycling of thin film photovoltaic modules. Resour. Conserv. Recycl. 54 (10), 711–718. Celik, I., Song, Z., Phillips, A.B., Heben, M.J., Apul, D., 2018. Life cycle analysis of metals in emerging photovoltaic (PV) technologies: a modeling approach to estimate use phase leaching. J. Clean. Prod. 186, 632–639. Chen, H.H., Pang, C., 2010. Organizational forms for knowledge management in photovoltaic solar energy industry. Knowledge Based Syst. 23 (8), 924–933. Cheng, A., 2014. Effects of waste material from solar panels on mechanical properties and durability of cement based materials. Mater. Res. Innov. 18, 344–349. Choi, J.-K., Fthenakis, V., 2010a. Design and optimization of photovoltaics recycling infrastructure. Environ. Sci. Technol. 44 (22), 8678–8683.

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Resources, Conservation & Recycling 146 (2019) 1–16

S. Mahmoudi, et al. Choi, J.K., Fthenakis, V., 2010b. Economic feasibility of recycling photovoltaic modules. J. Ind. Ecol. 14 (6), 947–964. Choi, J.K., Fthenakis, V., 2014. Crystalline silicon photovoltaic recycling planning: macro and micro perspectives. J. Clean. Prod. 66, 443–449. Collins, M.K., Anctil, A., 2017. Implications for current regulatory waste toxicity characterisation methods from analysing metal and metalloid leaching from photovoltaic modules. Int. J. Sustain. Energy 36 (6), 531–544. Commission, E., 2008. Directive 2008/98/EC of the European Parliament and of the Council of 19 November 2008 on Waste and Repealing Certain Directives (Waste Framework Directive). LexUriServ. do. . Corcelli, F., Ripa, M., Ulgiati, S., 2017. End-of-life treatment of crystalline silicon photovoltaic panels. An emergy-based case study. J. Clean. Prod. 161, 1129–1142. Cucchiella, F., D’Adamo, I., Rosa, P., 2015. End-of-life of used photovoltaic modules: a financial analysis. Renew. Sustain. Energy Rev. 47, 552–561. Cyrs, W.D., Avens, H.J., Capshaw, Z.A., Kingsbury, R.A., Sahmel, J., Tvermoes, B.E., 2014. Landfill waste and recycling: use of a screening-level risk assessment tool for end-of-life cadmium telluride (CdTe) thin-film photovoltaic (PV) panels. Energy Policy 68, 524–533. D’Adamo, I., Miliacca, M., Rosa, P., 2017. Economic feasibility for recycling of waste crystalline silicon photovoltaic modules. Int. J. Photoenergy 6. Dias, P., Javimczik, S., Benevit, M., Veit, H., Bernardes, A.M., 2016. Recycling WEEE: extraction and concentration of silver from waste crystalline silicon photovoltaic modules. Waste Manag. 57, 220–225. Dias, P., Javimczik, S., Benevit, M., Veit, H., 2017. Recycling WEEE: polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules. Waste Manag. 60, 716–722. Dias, P., Bernardes, A.M., Huda, N., 2018a. Waste electrical and electronic equipment (WEEE) management: an analysis on the australian e-waste recycling scheme. J. Clean. Prod. 197, 750–764. Dias, P., Machado, A., Huda, N., Bernardes, A.M., 2018b. Waste electric and electronic equipment (WEEE) management: a study on the Brazilian recycling routes. J. Clean. Prod. 174, 7–16. Doi, T., Tsuda, I., Unagida, H., Murata, A., Sakuta, K., Kurokawa, K., 2001. Experimental study on PV module recycling with organic solvent method. Sol. Energy Mater. Sol. Cells 67 (1–4), 397–403. Dominguez, A., Geyer, R., 2017. Photovoltaic waste assessment in Mexico. Resour. Conserv. Recycl. 127, 29–41. Dytrych, P., Bumba, J., Kastanek, F., Fajgar, R., Kostejn, M., Solcova, O., 2017. Waste photovoltaic panels for ultrapure silicon and hydrogen through the low-temperature magnesium silicide. Ind. Eng. Chem. Res. 56 (45), 12864–12870. Fthenakis, V.M., 2000. End-of-life management and recycling of PV modules. Energy Policy 28 (14), 1051–1058. Fthenakis, V.M., Wang, W., 2006. Extraction and separation of Cd and Te from cadmium telluride photovoltaic manufacturing scrap. Prog. Photovolt. 14 (4), 363–371. Giacchetta, G., Leporini, M., Marchetti, B., 2013. Evaluation of the environmental benefits of new high value process for the management of the end of life of thin film photovoltaic modules. J. Clean. Prod. 51, 214–224. Goe, M., Gaustad, G., 2016. Estimating direct climate impacts of end-of-life solar photovoltaic recovery. Sol. Energy Mater. Sol. Cells 156, 27–36. Granata, G., Pagnanelli, F., Moscardini, E., Havlik, T., Toro, L., 2014. Recycling of photovoltaic panels by physical operations. Sol. Energy Mater. Sol. Cells 123, 239–248. Grant, M.J., Booth, A., 2009. A typology of reviews: an analysis of 14 review types and associated methodologies. Health Info. Libr. J. 26 (2), 91–108. Hao, H.C., Lin, K.L., Wang, D.Y., Chao, S.J., Shiu, H.S., Cheng, T.W., Hwang, C.L., 2013. Utilization of solar panel waste glass for metakaolinite-based geopolymer synthesis. Environ. Prog. Sustain. Energy 32 (3), 797–803. Hao, H., Lin, K.L., Wang, D., Chao, S.J., Shiu, H.S., Cheng, T.W., Hwang, C.L., 2015. Elucidating characteristics of geopolymer with solar panel waste glass. Environ. Eng. Manage. J. 14 (1), 79–87. Hsueh, J.T., Lin, C.Y., 2015. Constructing a network model to rank the optimal strategy for implementing the sorting process in reverse logistics: case study of photovoltaic industry. Clean Technol. Environ. Policy 17 (1), 155–174. Huang, T.Y., Selvaraj, B., Lin, H.Y., Sheu, H.S., Song, Y.F., Wang, C.C., Hwang, B.J., Wut, N.L., 2016. Exploring an interesting Si source from photovoltaic industry waste and engineering it as a Li-Ion battery high-capacity anode. ACS Sustain. Chem. Eng. 4 (10), 5769–5775. Huang, B.J., Zhao, J., Chai, J.Y., Xue, B., Zhao, F., Wang, X.Y., 2017. Environmental influence assessment of China’s multi-crystalline silicon (multi-Si) photovoltaic modules considering recycling process. Sol. Energy 143, 132–141. IEA, 2018. IEA PVPS Trends 2018 in Photovoltaic Applications. IRENA: Stephanie Weckend, I.-P. A. W, Garvin Heath, 2016. End-of-Life Management: Solar Photovoltaic Panels. IRENA and IEA-PVPS. Islam, M.T., Huda, N., 2018. Reverse logistics and closed-loop supply chain of Waste Electrical and Electronic Equipment (WEEE)/E-waste: a comprehensive literature review. Resour. Conserv. Recycl. 137, 48–75. Kang, S., Yoo, S., Lee, J., Boo, B., Ryu, H., 2012. Experimental investigations for recycling of silicon and glass from waste photovoltaic modules. Renew. Energy 47, 152–159. Kim, S., Jeong, B., 2016. Closed-loop supply chain planning model for a photovoltaic system manufacturer with internal and external recycling. Sustainability 8 (7), 17. Kim, Y., Lee, J., 2012. Dissolution of ethylene vinyl acetate in crystalline silicon PV modules using ultrasonic irradiation and organic solvent. Sol. Energy Mater. Sol. Cells 98, 317–322. Klugmann-Radziemska, E., Ostrowski, P., Drabczyk, K., Panek, P., Szkodo, M., 2010. Experimental validation of crystalline silicon solar cells recycling by thermal and chemical methods. Sol. Energy Mater. Sol. Cells 94 (12), 2275–2282. Kreiger, M.A., Shonnard, D.R., Pearce, J.M., 2013. Life cycle analysis of silane recycling in

amorphous silicon-based solar photovoltaic manufacturing. Resour. Conserv. Recycl. 70, 44–49. Kuroiwa, K., Ohura, S., Morisada, S., Ohto, K., Kawakita, H., Matsuo, Y., Fukuda, D., 2014. Recovery of germanium from waste solar panels using ion-exchange membrane and solvent extraction. Miner. Eng. 55, 181–185. Latunussa, C.E.L., Ardente, F., Blengini, G.A., Mancini, L., 2016. Life Cycle Assessment of an innovative recycling process for crystalline silicon photovoltaic panels. Sol. Energy Mater. Sol. Cells 156, 101–111. Lee, J.K., Lee, J.S., Ahn, Y.S., Kang, G.H., Song, H.E., Lee, J.I., Kang, M.G., Cho, C.H., 2017. Photovoltaic performance of c-Si wafer reclaimed from end-of-life solar cell using various mixing ratios of HF and HNO3. Sol. Energy Mater. Sol. Cells 160, 301–306. Lin, C.Y., Shiue, Y.C., 2013. An application of AHP and sensitivity analysis for measuring the best strategy of reverse logistics: a case study of photovoltaic industry chain. J. Test. Eval. 41 (3), 386–397. Lin, K.L., Chu, T.C., Cheng, C.J., Lee, C.H., Chang, T.C., Wang, K.S., 2012. Recycling solar panel waste glass sintered as glass-ceramics. Environ. Prog. Sustain. Energy 31 (4), 612–618. Lin, K.L., Huang, L.S., Shie, J.L., Cheng, C.J., Lee, C.H., Chang, T.C., 2013. Elucidating the effects of solar panel waste glass substitution on the physical and mechanical characteristics of clay bricks. Environ. Technol. 34 (1), 15–24. Lin, K.L., Lee, T.C., Hwang, C.L., 2015. Effects of sintering temperature on the characteristics of solar panel waste glass in the production of ceramic tiles. J. Mater. Cycles Waste Manag. 17 (1), 194–200. Lu, B., Ma, B.J., Yu, R.Z., Lu, Q., Cai, S.Y., Chen, M.F., Wu, Z.Y., Xiang, K.X., Wang, X.Y., 2017. Photovoltaic monocrystalline silicon waste-derived hierarchical silicon/flake graphite/carbon composite as low-cost and high-capacity anode for lithium-ion batteries. Chemistryselect 2 (12), 3479–3489. Ma, C.M., Ruan, R.T., 2013. Adsorption of toluene on mesoporous materials from waste solar panel as silica source. Appl. Clay Sci. 80–81, 196–201. Malandrino, O., Sica, D., Testa, M., Supino, S., 2017. Policies and measures for sustainable management of solar panel end-of-life in Italy. Sustainability 9 (4), 481. Marwede, M., Reller, A., 2012. Future recycling flows of tellurium from cadmium telluride photovoltaic waste. Resour. Conserv. Recycl. 69, 35–49. Marwede, M., Reller, A., 2014. Estimation of life cycle material costs of cadmium telluride–and copper indium gallium diselenide–photovoltaic absorber materials based on life cycle material flows. J. Ind. Ecol. 18 (2), 254–267. Marwede, M., Berger, W., Schlummer, M., Maurer, A., Reller, A., 2013. Recycling paths for thin-film chalcogenide photovoltaic waste – current feasible processes. Renew. Energy 55, 220–229. McDonald, N.C., Pearce, J.M., 2010. Producer responsibility and recycling solar photovoltaic modules. Energy Policy 38 (11), 7041–7047. Menezes, S., 2001. Electrochemical approach for removal, separation and retrieval of CdTe and CdS films from PV module waste. Thin Solid Films 387 (1–2), 175–178. Moher, D., Liberati, A., Tetzlaff, J., Altman, D.G., P. Group, 2009. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med. 6 (7), e1000097. Pagnanelli, F., Moscardini, E., Atia, T.A., Toro, L., 2016. Photovoltaic panel recycling: from type-selective processes to flexible apparatus for simultaneous treatment of different types. Trans. Inst. Mining Metall. Sect. C-Miner. Process. Extr. Metall. 125 (4), 221–227. Pagnanelli, F., Moscardini, E., Granata, G., Atia, T.A., Altimari, P., Havlik, T., Toro, L., 2017. Physical and chemical treatment of end of life panels: an integrated automatic approach viable for different photovoltaic technologies. Waste Manag. 59, 422–431. Paiano, A., 2015. Photovoltaic waste assessment in Italy. Renew. Sustain. Energy Rev. 41, 99–112. Park, J., Park, N., 2014. Wet etching processes for recycling crystalline silicon solar cells from end-of-life photovoltaic modules. RSC Adv. 4 (66), 34823–34829. Peeters, J.R., Altamirano, D., Dewulf, W., Duflou, J.R., 2017. Forecasting the composition of emerging waste streams with sensitivity analysis: a case study for photovoltaic (PV) panels in Flanders. Resour. Conserv. Recycl. 120, 14–26. Petticrew, M., Roberts, H., 2006. Systematic Reviews in the Social Sciences: A Practical Guide. Blackwell Publishing, Malden, MA. Pickering, C., Byrne, J., 2014. The benefits of publishing systematic quantitative literature reviews for PhD candidates and other early-career researchers. High. Educ. Res. Dev. 33 (3), 534–548. Pickering, C., Grignon, J., Steven, R., Guitart, D., Byrne, J., 2015. Publishing not perishing: how research students transition from novice to knowledgeable using systematic quantitative literature reviews. Stud. High. Educ. 40 (10), 1756–1769. Quercia, G., van der Putten, J.J.G., Huesken, G., Brouwers, H.J.H., 2013. Photovoltaic’s silica-rich waste sludge as supplementary cementitious material (SCM). Cem. Concr. Res. 54, 161–179. Radziemska, E., Ostrowski, P., Seramak, T., 2009. Chemical treatment of crystalline silicon solar cells as a main stage of pv modules recycling. Ecol. Chem. Eng. S-Chemia I Inzynieria Ekologiczna S 16 (3), 379–387. Radziemska, E., Ostrowski, P., Cenian, A., Sawczak, M., 2010a. Chemical, thermal and laser processes in recycling of photovoltaic silicon solar cells and modules. Ecol. Chem. Eng. S-Chemia I Inzynieria Ekologiczna S 17 (3), 385–391. Radziemska, E., Ostrowski, P., Cienian, A., Sawczak, M., 2010b. Chemical, thermal and laser processes in recycling of photovoltaic silicon solar cells and modules. Ecol. Chem. Eng. S 17 (3), 385–391. Raugei, M., Isasa, M., Palmer, P.F., 2012. Potential Cd emissions from end-of-life CdTe PV. Int. J. Life Cycle Assess. 17 (2), 192–198. Ravikumar, D., Sinha, P., Seager, T.P., Fraser, M.P., 2016. An anticipatory approach to quantify energetics of recycling CdTe photovoltaic systems. Prog. Photovolt. 24 (5), 735–746.

15

Resources, Conservation & Recycling 146 (2019) 1–16

S. Mahmoudi, et al. Redlinger, M., Eggert, R., Woodhouse, M., 2015. Evaluating the availability of gallium, indium, and tellurium from recycled photovoltaic modules. Sol. Energy Mater. Sol. Cells 138, 58–71. Rocchetti, L., Beolchini, F., 2015. Recovery of valuable materials from end-of-life thinfilm photovoltaic panels: environmental impact assessment of different management options. J. Clean. Prod. 89, 59–64. Savvilotidou, V., Antoniou, A., Gidarakos, E., 2017. Toxicity assessment and feasible recycling process for amorphous silicon and CIS waste photovoltaic panels. Waste Manag. 59, 394–402. Segebade, C., Hedrich, M., Haase, O., Baede, B., 2008. Large sample activation analysis: monitoring of photovoltaic module recycling using radioanalytical methods. J. Radioanal. Nucl. Chem. 276 (1), 29–33. Shin, J., Park, J., Park, N., 2017. A method to recycle silicon wafer from end-of -life photovoltaic module and solar panels by using recycled silicon wafers. Sol. Energy Mater. Sol. Cells 162, 1–6. Sica, D., Malandrino, O., Supino, S., Testa, M., Lucchetti, M.C., 2017. Management of endof-life photovoltaic panels as a step towards a circular economy. Renew. Sustain. Energy Rev. 82, 2934–2945. Sinha, P., Kriegner, C.J., Schew, W.A., Kaczmar, S.W., Traister, M., Wilson, D.J., 2008. Regulatory policy governing cadmium-telluride photovoltaics: a case study contrasting life cycle management with the precautionary principle. Energy Policy 36 (1), 381–387. Smith, Y.R., Nagel, J.R., Rajamani, R.K., et al., 2017. In: Zhang, L., Drelich, J.W., Neelameggham, N.R. (Eds.), Electrodynamic Eddy Current Separation of End-of-Life PV Materials. Energy Technology 2017: Carbon Dioxide Management and Other Technologies. Cham, Springer Int Publishing Ag, pp. 379–386. Solangi, K., Islam, M., Saidur, R., Rahim, N., Fayaz, H., 2011. A review on global solar energy policy. Renew. Sustain. Energy Rev. 15 (4), 2149–2163. Tammaro, M., Rimauro, J., Fiandra, V., Salluzzo, A., 2015. Thermal treatment of waste photovoltaic module for recovery and recycling: experimental assessment of the presence of metals in the gas emissions and in the ashes. Renew. Energy 81, 103–112. Tao, J., Yu, S.R., 2015. Review on feasible recycling pathways and technologies of solar photovoltaic modules. Sol. Energy Mater. Sol. Cells 141, 108–124.

Van Eck, N.J., Waltman, L., 2010. Software survey: VOSviewer, a computer program for bibliometric mapping. Scientometrics 84 (2), 523–538. Vellini, M., Gambini, M., Prattella, V., 2017. Environmental impacts of PV technology throughout the life cycle: importance of the end-of-life management for Si-panels and CdTe-panels. Energy 138, 1099–1111. Xu, L., Zhang, S., Yang, M., Li, W., Xu, J., 2018a. Environmental effects of China’s solar photovoltaic industry during 2011–2016: a life cycle assessment approach. J. Clean. Prod. 170, 310–329. Xu, Y., Li, J., Tan, Q., Peters, A.L., Yang, C., 2018b. Global Status of Recycling Waste Solar Panels: A Review. Waste Management. Yi, Y.K., Kim, H.S., Tran, T., Hong, S.K., Kim, M.J., 2014. Recovering valuable metals from recycled photovoltaic modules. J. Air Waste Manage. Assoc. 64 (7), 797–807. Zeng, D.W., Born, M., Wambach, K., 2004. Pyrolysis of EVA and its application in recycling of photovoltaic modules. J. Environ. Sci. 16 (6), 889–893. Zeng, X., Yang, C., Chiang, J.F., Li, J., 2017. Innovating e-waste management: from macroscopic to microscopic scales. Sci. Total Environ. 575, 1–5. Zhang, T., Dong, Z.B., Qu, F., Ding, F.Z., Peng, X.Y., Wang, H.Y., Gu, H.W., 2014. Removal of CdTe in acidic media by magnetic ion-exchange resin: a potential recycling methodology for cadmium telluride photovoltaic waste. J. Hazard. Mater. 279, 597–604. Zhang, Y., Hu, Y., Zeng, H.M., Zhong, L., Liu, K.W., Cao, H.M., Li, W., Yan, H.J., 2017a. Silicon carbide recovered from photovoltaic industry waste as photocatalysts for hydrogen production. J. Hazard. Mater. 329, 22–29. Zhang, Z.S., Sun, B., Yang, J., Wei, Y.S., He, S.J., 2017b. Electrostatic separation for recycling silver, silicon and polyethylene terephthalate from waste photovoltaic cells. Mod. Phys. Lett. B 31 (11), 11. Zimmermann, Y.S., Schaffer, A., Corvini, P.F.X., Lenz, M., 2013. Thin-film photovoltaic cells: long-term metal(loid) leaching at their end-of-Life. Environ. Sci. Technol. 47 (22), 13151–13159. Zimmermann, Y.S., Niewersch, C., Lenz, M., Kul, Z.Z., Corvini, P.F.X., Schaffer, A., Wintgens, T., 2014. Recycling of indium from CIGS photovoltaic cells: potential of combining acid-resistant nanofiltration with liquid-liquid extraction. Environ. Sci. Technol. 48 (22), 13412–13418.

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