(Invited) Glass and Metal Separation Technology to Improve Solar Panel Recycling
Authors: Ito Masafumi , Doi Taisuke 
Published: December 2024

NPC Inc.(“NPC”) has been developing and assembling photovoltaic panel manufacturing equipment for more than 30 years, providing domestic and overseas module manufacturers with equipment designed for various types of modules, including crystalline and thin-film type. NPC’s proprietary “Hot Knife Separation Method” has successfully realized the separation of glass and metal, contributing to the solar panel recycling sector.
1. INTRODUCTION
The Japanese solar panel market has grown rapidly due to the introduction of feed-in tariff in 2012. However, a massive amount of end of life solar panels are assumed to be discarded in the future. According to the Agency for Natural Resources and Energy forecast, this will peak between 2025 and 2037, resulting in the discharge of approx. 170,000 to 280,000 tons/year. Under such circumstances, NPC has been conducting R&D of solar panel recycling process and panel disassembly equipment since 2014, utilizing its existing business, solar panel manufacturing equipment. The New Energy and Industrial Technology Development Organization (NEDO), a national research and development agency, has begun accepting applications for the "Photovoltaic Recycling Technology Development Project," and NPC participated in the project from FY2015-2018 for the purpose of " Development of complete recycling technology of glass and metals by separation method using hot knife" and have successfully led to commercialization of this technology.
2. ISSUE & SOLUTION FOR PANEL RECYCLING
Most of panel recycling companies in Japan are using shredding systems to process broken solar panels and aluminum frames are recycled. However, valuable resources such as glass/cell/EVA are crushed and landfilled as industrial waste or used for road materials, resulting in high environmental impact and cost. To tackle this issue, NPC has developed the “Hot Knife Separation Method’’, enabling auto-processing of separating solar cells/EVA/backsheet ("cell/EVA sheet") from solar panels without breaking the glass.
3. HOT KNIFE
A hot knife heated to 300°C separates the glass from the other components without breaking the glass. The other components EVA/solar cell/backsheet can be separated into sheets. This method has been developed as reverse process utilizing NPC’s core technology and experience from photovoltaic panel lamination.
The surface of a solar panel glass is embossed in order to adhere EVA. Therefore, about 0.1 mm of EVA remains on the glass surface. The glass separated without breakage is highly separable from metals and thus can be used as resources for making glass fiber, glass sand, etc. in Japan. Moreover, in Europe it is used as resources for manufacturing flat glass.
4. SOLAR PANEL RECYCLING LINE
In order to recover glass without breaking it, NPC has developed and marketed an automated line combined with this unique hot knife separation system. The process is divided into the below three steps, and after the panels are loaded in the machine, they are automatically separated into their respective materials.
4.1 J-Box Separator
Automatically removes the J-Box using a scraper; the J-Box cables contain copper wire, which can be recycled as copper scrap.
4.2 Frame Separator
Automatically transported to the next process, where a mechanical chuck is used to separate all four sides of the frames, without breaking the glass. These frames are made of aluminum and can be recycled.
4.3 Glass Separator
Finally, the panel will be automatically transported to the final process of glass separation to separate the glass from the cell/EVA sheet without breakage. As described above, a blade heated to 300℃ melts the EVA layer to separate glass from other components.
5. SEMI-AUTOMATED FRAME & J-BOX SEPARATOR
NPC also developed the Semi-automated Frame & J-Box Separator, which removes 4 frames and J-Box automatically in approx. 40 seconds. Thanks to its compact size and weight, this type of machine can be loaded on trucks, and it will function as a mobile separator to disassemble the panels at the site of solar power plant using only power generators. This machine has been delivered to a waste management company in Japan and acquired on-site disassembly permission in the relevant prefecture.
6. SUMMARY
NPC is further advancing its panel disassembly technology by receiving feedback from our customers using our recycling machines in Japan and overseas. Furthermore, research is underway to develop a process that leaves less residual material on the glass.

Figure 1