Waste generation and management due to solar power

The increasing awareness about climate change and the push by the public and governments to shift from fossil fuels to renewable sources of energy. One source that has gained much attention in recent times is solar power. Unlike fossil fuels, power generation using solar panels does not generate greenhouse gases or any other pollutant during the generation itself, but it does not mean it is a completely clean source of power. First, solar panels have to be manufactured, and manufacturing by nature is a polluting process. More recently,  there has been another concern, namely the disposal of solar panels once their life is over. 

By weight, a solar panel majorly consists of glass and its aluminum frame. It is possible to recycle these two and silicon (the highest percentage by value) by itself does not have much environmental impact. However, there are many other materials like antimony, cadmium, lead, polymers and other heavy metals[1] that if not taken care could leach into the environment and cause significant damage. 

At present, there is no policy in place in India to ensure proper recycling/disposal of used solar panels by plant operators or manufacturers. MNRE's guidelines for setting up of grid-connected solar power plans [2] mention in the very end that solar panels have to be recycled and disposed of according to  “e-waste (Management and Handling) Rules, 2011” notified by the Government and as revised and amended from time to time. However, the above-mentioned rules do not have any guidelines for proper management of "end of life" solar panels. 

The most recent step taken in this direction was the release of a concept note on "Management of Antimony Containing Glass from End-of-Life of the Solar PV Panels" released by MNRE[3]. This note recommends the following steps in order to handle SPGCA (solar panel glass containing antimony) :

• Recycling should be made mandatory in the long run.
• Antimony containing glass be separated from the normal glass. 
• The possibility of utilizing used solar panels by co-processing in cement kilns should also be explored
• The end-of-life solar panels are required to be collected and stored safely under a covered shed till the time the material is sent for recycling or the option for recycling is available
• It should be ensured that end-of-life solar panels shall never be disposed or dumped in open landfills as it may release Antimony into the environment
• Disposal of used solar panel glass in a secured landfill is not the preferred option. The option of disposal in a secured landfill may arise only in case the waste Antimony glass cannot be recycled even in the long run
• Only the non-recyclable material in solar panel after removal of glass, aluminum and junction box, may be allowed for disposal through secured landfills

This is definitely a step in a positive direction but could take some time to transform into a proper policy/ regulation. Secondly, the above note discusses only the disposal and recycling of antimony containing glass used in solar panels, there is still no policy in place for the disposal of other hazardous wastes. 

Hazardous materials in new solar cell technologies

New solar cell technologies like Cd-Te and perovskite solar cells promise lower costs and better efficiencies in some cases[4][5]. However, these technologies contain materials like Cd (CdTe cells) and lead (perovskites) as a core component. Due to their presence, these could not have made to the market owing to RoHS rules. However, photo-voltaic technologies have been exempt from these regulations in the EU[6]. However, if these technologies are adopted at a large scale it could lead to a situation where it could become difficult to properly manage the used solar panels. Some researchers have recently started to explore other metals (like tin) to replace lead in perovskites but these are not stable enough to be of practical use[7]. 

In summary, as solar power develops further we need to ensure that there are proper guidelines in place to enable proper disposal and recycling of generated waste, otherwise, we might be exchanging one kind of environmental with another. 

References

1. https://bridgetoindia.com/report/managing-indias-pv-module-waste/
2.  https://mnre.gov.in/file-manager/UserFiles/Draft-EPC-SBG-19072016.pdf
3. https://mnre.gov.in/sites/default/files/webform/notices/DraftBluePrintAntimony.pdf
4. https://www.nrel.gov/pv/cadmium-telluride-solar-cells.html
5. https://www.nrel.gov/pv/cadmium-telluride-solar-cells.html
6. https://eur-lex.europa.eu/legal-content/en/TXT/?uri=celex:32011L0065
7. https://pubs.rsc.org/en/content/articlelanding/2019/qm/c8qm00611c#!divAbstract