# The Design Value for Recycling End-of-Life Photovoltaic Panels
## 2 Challenges and Opportunities for Photovoltaic Energy  
The use of energy from PV panels is considered a \"low environmental impact\" choice since it exploits a 'clean' source such as the sun, avoiding the production of greenhouse gases. In 2018, photovoltaics began to be the fastest growing energy technology in the world. According to the latest authoritative reports [11; 12; 13], the market for PV panels has been continuously increasing. PV electricity capacity has continuously grown exponentially with only a few disturbances, mainly due to strong increases in the costs of raw materials and shipments. As a result of new installations, in 2021, there was a cumulative global capacity of 942 GW (Figure 4). In 2021, there was a total annual addition of 175 GW, with an increase of 36 GW compared to 2020. The leading countries for cumulative PV capacity are China, the United States, Japan, India and Germany, and the leading countries for per capita capacity are Australia, the Netherlands and Germany (Figure 5). Currently, of all the PV panels installed globally, China holds the largest share with 31%, followed by the United States (15%) and India (7%) [11]. Figure 4: Exponential growth of PV energy in the years 2011–2021 (source [11]). Figure 3: Main research steps. However, the increase in the installation of PV panels means an increase in the amount of waste produced when these panels reach their EoL. Considering the study of [PERSON] et al. [14], a dizzying increase will be registered in metric tons per year of PV panel waste over the next two decades. In fact, it is expected that the European Union will generate 500,000 tons of waste per year compared to the current 30,000 tons. Compared to the current situation of PV panels installed (Figure 4), some authors [15] estimate an exponential increase, especially in Europe and in Italy, resulting in a dramatic increase in waste from PV between now and 2050 (Table 1). Several studies [16; 17; 18; 19] highlight the critical issues of PV panels in EoL phases due to the risk of releasing highly polluting substances into the soil, groundwater or the atmosphere. This is particularly true if the modules are disposed of as they are in landfills or if they undergo incineration processes, in which they can release highly polluting substances into the soil, groundwater or the atmosphere. Hence, it is important to develop adequate EoL management processes through appropriate disposal/recycling technologies in an environmentally and economically sustainable way. Today, technologies capable of recycling 95-99% of PV panels materials (e.g., glass, copper, aluminum, etc.) do exist. Most of the recyclable materials in PV panels are based on glass with about 68% by weight, aluminum with about 15% by weight, high-purity silicon with about 3% by weight and copper cables with about 1% by weight (Figure 6). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Year** & **2013** & **2020** & **2030** & **2040** & **2050** \\ \hline
**Europe** & 11,395 & 33,000 & 133,000 & 4,000,000 & 9,500,000 \\
**Italy** & 1757 & 1000 & 5000 & 1,000,000 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Estimate of tons of waste from PV panels in Europe and Italy. Figure 5: PV panels globally installed in 2021. With reference to the percentage of recyclability of materials, different recycling methods achieve different results. It is worth remembering that some elements are present in very low percentages. The opportunity of their recovery at their EoL depends not only on the technical possibility of carrying out the action, but also on the cost/benefit of the process in economic terms and therefore on the correct design with which the panels are designed, foreseeing their entire life cycle. Finally, it is necessary to highlight the considerable benefits that are obtained by increasing the average life (durability) of the panels while maintaining high efficiency. Figure 7 highlights the accumulation of non-recycled PV panels in the case that their useful life is 30 years.