A new report from the International Energy Agency Photovoltaic Power Systems Programme (IEA PVPS) under task 12 sees potential in hot knife delamination technology for solar module recycling as it efficiently recovers aluminum and glass, and separates the backsheet, with a lower environmental impact.
Known to be the single most challenging step in high-value solar module recycling process, the delamination process determines the economic value of the recovered materials as well as their environmental performance.
The hot knife delamination process of crystalline silicon (c-Si) PV modules is automated in a PV module assembly line comprising a junction box, a frame separator and a glass separator.
After removing the junction box, cables are removed from the separated junction box, followed by removal of the aluminum frame and then separation of the glass from the laminate backsheet, according to the report.
"We find that the hot knife treatment of decommissioned c-Si PV modules causes a very small share of the life cycle environmental impacts of a 3-kWp PV system mounted on a slanted roof in Europe, according to the analysed environmental indicators," reads the report. "The highest contribution of delamination is observed for the climate change impacts, mainly caused by transport logistics (module collection and delivery to the hot knife treatment site) and electricity consumption."
Authors of the report also believe the use of recovered materials using such a process, instead of virgin materials, can bring down solar PV technology's lifecycle impact by 80% to 98%, depending on the impact category.
Currently, the hot knife delamination technology is being used in one of the world's largest commercial– scale PV recycling facilities by ENVIE in Bordeaux, France.
Researchers are confident that once the technology is deployed at a larger scale and in other applications, gains in energy and consumables efficiencies can be expected.
While the report writers depend on primary data from hot knife technology manufacturer NPC Incorporated of Japan, they say their own findings are consistent with other literature. The Japanese machine manufacturer refers to this proprietary process as 'separation method using a heated blade'.
Titled Life Cycle Assessment of Crystalline Silicon Photovoltaic Module Delamination with Hot Knife Technology, the report completes a life cycle assessment (LCA) of the hot knife delamination technology, but does not cover the subsequent processes of recovering copper and silver due to lack of available data. It can be downloaded for free from IEA PVPS website.
Participants from the solar PV industry explored solar module recycling as part of the discussion on sustainability during TaiyangNews Solar & Sustainability Conference earlier this year. Presentation recordings and conference summary can be accessed here.