Adhesives for solar panels
Silicone adhesives are used to bond the aluminum frame to the glass laminate and to secure the junction box on the back of solar panels, and they must resist UV, withstand rain and sun, and maintain adhesion for more than 25 years outdoors.
A solar panel typically carries a power output warranty of 25 to 30 years. Throughout that time, the bonds must endure surface temperatures of up to 85 °C at midday, night dew, storms and, in some export markets, snow loads. Silicone adhesive is almost the default choice for these locations.
Three adhesive locations on a solar panel
- Frame bonding: adhesive is dispensed into the aluminum frame channel before the laminate is inserted, providing both mechanical retention and edge sealing.
- Junction box bonding: secures the box to the backsheet and withstands the pull of the cables.
- Junction box potting: fills the box to protect the diodes and ribbon solder joints from moisture.
Properties that determine durability
The Si–O bond in silicone has higher energy than the C–C bond in many organic polymers, so the material is less susceptible to UV degradation. Silicone also stays elastic at both very low and high temperatures, accommodating the differential expansion between glass, aluminum and backsheet.
- Good adhesion to glass, anodized aluminum and PET- or fluoropolymer-based backsheets.
- Tensile strength of approximately 1.5 to 3 MPa, elongation above 200%.
- Withstands damp heat testing at 85 °C, 85% RH for 1,000 hours per IEC 61215.
One-component or two-component
One-component adhesives cure with atmospheric moisture and are easy to use but require holding time before packing. Two-component adhesives cure quickly and uniformly through their depth, making them suitable for high-capacity lines and significantly reducing waiting time on the conveyor.
The most common defect we see is not adhesive quality but the amount of adhesive in the frame channel. A short gap in the bead is enough to let water reach the laminate edge after a few rainy seasons. — AMS Technical Service Engineer
Line control
Install bead inspection sensors, periodically weigh the amount of adhesive per frame, and check adhesion with peel tests on samples every shift. With two-component adhesives, the metering equipment should have its mix ratio calibrated regularly.
For junction box potting, choose a low-viscosity grade that flows fully around the diodes and solder joints, with moderate thermal conductivity to help the bypass diodes dissipate heat when part of the panel is shaded. A short cure time allows panels to move on to electrical testing sooner.
Contact AMS Vietnam to request silicone adhesive samples for your solar panel assembly line.
