# The Design Value for Recycling End-of-Life Photovoltaic Panels
## 3 Effective PV Panel Design Methods for Recycling at EoL
### Design for Durability  
The standards IEC 61215-1/-1/2:2016, ISO 61730-1/2:2016, ISO 9001, ISO 14001, ISO 50001 (Table 4) establish that PV panels and PV modules must be guaranteed for 25 years. They set the tests that they must pass and the minimum values of resistance and performance that they must have (Tables 4-6). In particular, they set the limits of  
Figure 10: Recycling material from a 21 kg commercial PV panel.  
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multirow{2}{*}{**Weight [kg]**} & **Costs of Recycling [**c]** & **Total Cost of Recycling [**c]** & **Material Value [**c]** & **Total Material Value [**c]** & **Net Profit [**c]** \\ \cline{1-1}  & & **[f/kg]** & **Recycling** & **Total Cost of Recycling [**c]** & **Material Value [**c]** & **Total Material Value [**c]** & **Net Profit [**c]** \\ \hline Tempered glass & 15 & 2.54 & 38.1 & 150 \(\div\) 525 & 2250 \(\div\) 7875 & 2211.9 \(\div\) 7836.9 \\ Plastic & 2.8 & 0.22 & 0.616 & 3.08 \(\div\) 5.88 & 8.62 \(\div\) 16.46 & 8 \(\div\) 15.84 \\ Aluminum & 2 & 6.62 & 13.24 & 0.94 & 1.88 & \(-\)11.36 \\ Silicon & 1 & 3.04 & 3.04 & 25 \(\div\) 30 & 25 \(\div\) 30 & 21.96 \(\div\) 26.96 \\ Copper & 0.14 & 32.17 & 4.5 & 0.14 \(\div\) 1.12 & 0.02 \(\div\) 0.16 & \(-\)4.48 \(\div\) \(-\)4.34 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Cost of recycling, material value and net profit.  
All elements, except for the junction box and the frame, are inserted at the time of assembly into a laminator, whose temperature reaches 145\({}^{\circ}\). In a vacuum process, EVA is heated and fixes the parts together, isolating the PV cells to preserve them from external deterioration agents. In this process, it is very important that the last layer of EVA is perfectly adherent and positioned correctly, since, if of low quality and/or positioned incorrectly, it can cause the formation of small air bubbles between the layers that can affect the correct production of the panel.  
Over time, the thermo-mechanical stresses end up leading to the delamination of layers of EVA from the photovoltaic cell layer and the backsheet layer due to the creep phenomenon. In the following sections, an effective numerical method which makes it possible to evaluate this phenomenon and to predict the durability of the panel is described.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Failure Cause** & **Estimated Frequency** & **Description** & **Method to Avoid Damage** \\ \hline \multirow{6}{*}{_Falling debris, breakage for impacts and micro-cracks_} & \multirow{2}{*}{High} & \multicolumn{2}{c}{Scratches and breakage due to falling hail, debris, including whole branches, acorns, twigs, etc. Consequences of incorrect production, shipment and installation.} & \multirow{2}{*}{Produce small PV panels/small PV modules. Make bars in the panels.} \\  & & & Rust occurs when moisture penetrates the panel. Moisture leads to corrosion that becomes visible as a result of darker stains on the panel. Water damage caused by deterioration or old age. Spots on PV panels caused mainly by poorly welded connections or as a result of structural defect in the cells. It is a defect related to the discoloration of the panel. The causes that generate this defect are multiple, including the formation of microscopic cracks in the panel and the use of silver paste of defective frontal metallization. & \multirow{2}{*}{Control of the absolute quality of the cells during assembly.} \\  & & & Due to a voltage difference between the panel (grounded) and the grounding. & \\ \hline \hline \end{tabular}
\end{table}
Table 7: Damage/failure causes in PV panels.  
Figure 11: (**a**) Falling debris and breakage for impacts; (**b**) water damage; (**c**) contamination of snail traces.