Edge seal: Liquid-applied vs. tape

Solar panel manufacturing is complex and challenging for many reasons, with one of these challenges being the sealing of the panel against the weather elements to which it will be exposed. The process of edge sealing the panels can make or break the quality of the panel when it is exposed to weather elements. This case study is meant to explain the benefits of using dispensing equipment to complete the edge sealing process.
 

Simply put, moisture is the enemy of solar panels. Moisture ingress into the panel causes poor performance and premature failure, so properly sealing the panel against moisture is of utmost importance. Because of this importance, much time and effort are spent on this step of the manufacturing process.  

As engineers assess manufacturing quality and efficiency, the edge seal process remains top of mind because it has such an effect on the end product. As the demand for solar energy grows, the benefits from improving the edge seal process will pay dividends long into the future.

Traditionally, the edge seal process is done with a tape that seals the components together. The tape is applied manually or automatically. While tape has traditionally been the sealant of choice, a newer technology called pumpable solar edge tape (PSET) has proven itself to be a high-quality successor for this important manufacturing step. 
 

Edge sealing using tape has historically been the go-to for manufacturers, who apply the tape manually or with automated equipment. However, inefficiencies in time, material waste, and a lack of dimensional flexibility led to the industry looking to new, more versatile solutions.
 

Edge seal tape comes in reels, which are installed on the tape dispense head. During production, these reels must be frequently changed, which results in machine downtime and labour to make the change. This changeover adds a costly interruption to an otherwise streamlined manufacturing line.
 

In order to ensure complete edge seal coverage around the perimeter of the solar panel, edge seal tape is often overlapped in the corners and at the start/stop position. This overlapping of the tape causes significant squeeze-out of edge seal during the lamination process. This squeeze-out ends up as waste and needs to be manually trimmed from the panel. This additional step contributes to the overall waste of time and materials.
 

Edge seal tapes have a fixed width and thickness. If your products require several sizes of edge seal tape, this lack of flexibility to quickly make adjustments to the tape size and thickness contributes to the manufacturing process inefficiencies.
 

PSET is a polyisobutylene butyl rubber adhesive. This adhesive is used to effectively prevent outside moisture or other contamination from having a negative influence on the frameless solar panels. PSET is preferable over tape due to its: 

• Good ozone and weathering resistance
• Low permeability to gasses (air and moisture)
• High-energy absorption (mechanical strength)
• Good heat resistance (holds up well in sunlight and high temperatures)
• Low-temperature flexibility (does not become brittle or weak during low-temperature exposure)
• Ability to give tensile strength
   

For solar panel manufacturing, long-term success hinges on developing and perfecting the right process. Shifting from edge tape to PSET is a tool to improve your manufacturing efficiency and product quality, which sends the company on a good path to success. PSET has now been commonly used across this industry and is a reliable trend for solar panel manufacturing. The following benefits have been observed when companies switched to PSET processes.
 

The PSET liquid edge seal is applied in a continuous bead all the way around the perimeter of the solar panel. This eliminates the need for overlapping edge seal in the corners and start/stop areas, resulting in a clean and robust seam. A continuous uniform bead allows for much greater control of any squeeze-out and trimming required after lamination.
 

When material can be heated and pumped out of large drums, it eliminates the need to change tape reels, thus reducing manual labour and increasing machine productivity. Heated bulk dispense systems used in tandem with the edge seal material can continuously feed the automated machine and dispense head that apply the edge seal to the solar panel. 
 

For solar manufacturers looking to move from their legacy edge tape application to solar edge tape, Graco Therm-O-Flow paired with the Precision Gear Metering (PGM) system by Graco is the only worldwide end-to-end sealing edge solution. This system was created specifically for those looking to seamlessly dispense liquid edge seal and make adjustments to the bead quickly. And with throughput capability more than 200% better than the next competitor, this system will quickly benefit those looking to add the latest in hot-melt technology to improve their plant operations. 

As thermal heating and solar energy are already fundamentally “green” ventures, Graco looks to impact overall sustainability on a more holistic scale. Reach out to Graco today to discuss your solar application and see how we can assist with increasing your efficiency and product quality.