In 2025, solar power surged in Europe, with the European Commission (EC) calling it a “shining star of Europe’s clean transition” in a recent article. The EU’s solar photovoltaic (PV) capacity was estimated to reach 406 GW by the end of the year, compared to 338 GW in 2024. According to the EC, this “comfortably surpasses” the target outlined in the EU Solar Energy Strategy released in 2022, which set the goal of reaching 380 GW by 2025.
As installations grew rapidly alongside an exceptionally sunny summer last year, June 2025 was the first time in EU history that the sun was the primary source of electricity generated.
Similar records are being broken all around the world. According to Ember, solar generation increased by 27% year-on-year in the US and met 61% of America’s energy demand increase last year. China has already exceeded its 2030 targets for solar power and, in mid-2025, notably became the first country to surpass 1,000 GW of solar capacity.
As the demand for solar panels continues to rise, the silicon market is growing alongside it. Silicon’s semiconductor properties form the backbone of almost all PV cells, providing a winning combination of high efficiency, low costs, and long lifetimes. In addition to this, silicon-derived silicones play a key role in solar panel assembly. Silicones serve as encapsulants, seals, and adhesives, helping manufacturers protect fragile components from challenging conditions and join pieces together during the final assembly.
While silicones are not the only options available, they often stand out for their durability, flexibility, and production efficiency. Room temperature vulcanizing (RTV) silicones, for example, remain stable across a wide temperature range. They begin to break down at temperatures over 350°C, providing an inert silica deposit that is non-combustible and non-flammable.
Further high-performance characteristics of silicones have made them a popular choice in solar panel assembly. Below, we draw on expertise from Elkem Silicones to explore three key examples.
Sealing the frame
In solar panel assembly, aluminium frames provide structural support and rigidity for the individual panels, preventing them from bending or warping. High-quality adhesives are used to seal the metallic frame around the glass, creating a watertight seal to protect cells and wiring. In this application, manufacturers look for materials with good, long-lasting adhesion and strong mechanical performance, enabling the seal to withstand a degree of mechanical stress during assembly, transit, and installation. For this reason, good elasticity is vital, enabling the seal to flex while maintaining its integrity.
Over the course of a solar panel’s life, a wide variety of potentially damaging weather conditions come into play, and the seal must maintain integrity through all of these.
“Solar panels are exposed to wind, rain, UV, high temperatures, and very low temperatures – lots of very harsh conditions – so we need a sealing material that is very resistant to all these outside factors,” says Valentin Bacquet, Technical Service Manager for Industrial Assembly and Molding at Elkem Silicones.
At the same time, manufacturers also prioritise efficiency during production, which is why a rapid curing RTV system is ideal, combining strong adhesion and resistance with high throughputs.
“In solar panel assembly, the speed of production is very high; you need to make a large number of pieces very quickly to be profitable in this kind of market. Our 2k polycondensation silicone cures at room temperature quickly with strong adhesion,” explains Bacquet.
Potting electricals
Junction boxes wire the four connectors of the solar panel together in a protective enclosure. They serve as the output interface of the solar panel, gathering the electricity produced by the cells and transferring it to the external wiring. The long-term reliability of these connections is dependent on silicone potting materials, which protect the electrical components from moisture ingress, dust, and other external factors such as vibrations.
“All of the different conditions that the solar panel will face throughout its lifetime can make the connection very sensitive to dysfunction,” says Bacquet. “The potting is designed to protect and needs to be effective for at least 25 years. You can use a polyaddition silicone or polycondensation silicone, but most of the time our customers choose one of our 2k polycondensation products because it provides a bit of adhesion that makes the enclosure fully waterproof.”
These two-component RTV silicones (RTV-2) achieve their cure by rapidly crosslinking when the two components are mixed. In this application, one of the most important properties is the silicone’s light viscosity and good flowability, enabling full encapsulation of the complete junction box.
Bonding the junction box
Silicone adhesives are also used to bond the junction box to the back of the panel, fixing it in place securely with high strength. “The junction box is bonded onto the plastic back side of the panel,” explains Bacquet. “You don’t need any specific behaviour here other than adhesion and weather and temperature resistance, which are inherent properties for silicone. Most of the time, we suggest a one-component RTV silicone.”
One-part RTVs (RTV-1) provide a simple, ready-to-use material at a low cost. The silicone can be applied directly onto the mounting surface of the junction box and the parts can be assembled within minutes, providing long-lasting adhesion that will endure for decades despite extreme temperature fluctuations.
The continued growth of the solar power industry and other ‘green energy’ markets depends on reliable, high-performance materials that enable quick and easy manufacturing. To learn more about the role of silicones in the wider energy transition, please download the new report below.
