## 4 Conclusions  
The present study discussed different scenarios for the EoL of c-Si solar modules through the LCA methodology. It analysed the environmental impacts of each scenario based on the GWP, HTP-CE, HTP-nCE, FEuP, FEcP and ADP of the whole process of manufacturing c-Si solar modules (considering mono- and multi-crystalline silicon solar cells) from the raw materials until the EoL. The possible EoL scenarios considered were landfill, incineration, reuse and recycling (considering mechanical, thermal and chemical methods). The results validate the environmental benefits of the recycling processes when compared with other possible scenarios for all categories. With the assumptions made in this LCA, all recycling processes produce improved environmental outcomes. The main reason for that is that these processes can recover glass and silicon to be reused to manufacture new solar cells and modules. In this study, the recovery of other materials besides glass, aluminium and silicon was not considered. Hence, the cell production, particularly, presents higher ADP impacts from the recycling processes compared to the other EoL scenarios. This outcome could be lower with the adoption of more complex recycling processes that can recycle other substances, such as lead and silver. Especially for thermal recycling, the combination of other processes after the recovery of the glass needs to be addressed. Studies show that the combination of thermal and chemical methods can achieve good recycling rates and recover almost all materials from solar modules [7; 9; 42]. Figure 10: Inclusion of transportation on the final results for the EoL scenarios analysed for Resources (ReCiPe), considering that the landfill and incineration plants are within 50 km from the collection point in all cases. Another critical concern is the use of toxic substances during the chemical recycling treatment, which must be addressed. In this LCA, we considered tetrahydrofuran, o-dichlorobenzene and toluene, which show the most promising results. However, these substances present serious issues related to human health, fauna and flora. Alternative chemicals should be tested to decrease possibilities of environmental impacts associated with chemical routes for recycling solar modules. Transportation can add significant environmental impacts to all scenarios analysed. In this LCA, the maximum distance from the collection point to the treatment facility for the recycling methods to have lower environmental impacts than the other options studied was shown. For example, for recycling to be the best option, it must be no more than 80 km further away than a landfill or incineration plant when considering human health and ecosystems impacts (ReCiPe) and using a diesel truck as the transportation method. The impacts for resources depletion (ReCiPe) are also heavily impacted by the transportation method and, in this case, a distance of 100 km still shows the recycling processes as the best environmental option. In summary, the key finding of this study is that the possibility of recycling materials from solar modules can result in lower environmental impacts when compared with other EoL scenarios, i.e., landfill, incineration and reuse, based on the assumptions made in this LCA, but attention should be given to the transportation for all cases. Small fixed or portable recycling facilities could be considered, as could less damaging transport modes than road trucks. Attention should also be given to reducing the use of toxic substances during the chemical routes for recycling. The following are available online at [[http://www.mdpi.com/2076-3417/8/8/1396/s1](http://www.mdpi.com/2076-3417/8/8/1396/s1)]([http://www.mdpi.com/2076-3417/8/8/1396/s1](http://www.mdpi.com/2076-3417/8/8/1396/s1)), Table S1: Relative environmental impacts for different end-of-life scenarios considering multicrystalline silicon solar modules: landfill, incineration, reuse and recycling (thermal, chemical and mechanical).