Driven by the “dual carbon” goals, the photovoltaic industry has experienced rapid growth. As the core carrier of clean energy, the power-generation efficiency and service life of photovoltaic power plants directly determine the feasibility of large-scale industrial deployment. Photovoltaic modules are exposed for extended periods to harsh outdoor conditions, continuously subjected to intense ultraviolet radiation, alternating high and low temperatures, and weathering from wind and rain; among these, UV radiation is one of the primary factors leading to module performance degradation and reduced service life. Thanks to their unique molecular structure and outstanding UV resistance, silicone materials play a pivotal role in two critical applications—module encapsulation and backsheet coating—making them essential materials for ensuring the long-term stable operation of photovoltaic modules and supporting the achievement of sustained, high-efficiency power generation at photovoltaic power plants.

I. The Core Principle Behind the UV-Resistant Properties of Organosilicon Compounds

The UV resistance of organosilicon materials stems from their unique molecular structural characteristics. Unlike conventional polymers, which typically have carbon–carbon backbones, organosilicon polymers feature silicon–oxygen backbones. The Si–O bond energy is as high as 452 kJ/mol, significantly exceeding the 347 kJ/mol of the C–C bond, and the polymer chains adopt a stable helical conformation. Moreover, the organic substituents attached to the side chains further enhance molecular stability.

This structural feature ensures that, under intense ultraviolet irradiation, the silicone polymer chains are resistant to chain scission and degradation, thereby effectively mitigating UV-induced aging. At the same time, silicones exhibit excellent resistance to both high and low temperatures, as well as to damp heat and corrosion, making them ideally suited to meet the demanding long-term outdoor service requirements of photovoltaic modules. Furthermore, by incorporating light stabilizers and other modification strategies, the UV resistance of silicones can be further enhanced, extending their UV aging life to over 10,000 hours and ensuring stable core performance even after prolonged use.

II. Component Sealing: Silicone Forms the First Line of Defense Against UV Radiation

(1) Core Requirements for Sealing Photovoltaic Modules

The sealing performance of photovoltaic modules directly determines the safety of the internal solar cells and electrical circuits. Prolonged exposure to outdoor ultraviolet radiation can cause aging and cracking of conventional sealing materials, such as EVA and ordinary rubber, thereby compromising their sealing function. This allows moisture and dust to penetrate the module, leading to corrosion of the solar cells, short circuits in the electrical circuits, and ultimately resulting in power degradation or even failure of the module.

(2) UV-Resistant Advantages and Applications of Silicone Sealants

Thanks to its outstanding UV resistance, silicone sealant has become the material of choice for sealing photovoltaic modules, primarily used in critical areas such as the joints between the module frame and glass, potting of junction boxes, and interlayer sealing within the module. Its core advantages lie in three key aspects:

First, it exhibits outstanding resistance to UV-induced aging: even after prolonged exposure to outdoor UV radiation, it does not undergo yellowing, hardening, or embrittlement, thereby maintaining excellent elasticity and adhesion over the long term. Second, it provides superior sealing and protection, with a water vapor transmission rate reduced to below 1 g/(m²·day), effectively preventing the ingress of moisture and dust. This helps avoid inter-cell corrosion and PID (potential-induced degradation) in solar modules, while also delivering outstanding electrical insulation to prevent short circuits. Third, it demonstrates strong environmental adaptability: it maintains stable sealing performance across a wide temperature range from –50°C to 200°C, making it suitable for diverse climatic regions. Moreover, the flexible cured adhesive layer can buffer stress and impact, further enhancing module reliability.

Testing has shown that photovoltaic modules sealed with silicone exhibit stable sealing performance for more than 25 years under prolonged outdoor UV exposure, perfectly aligning with the design service life of the modules.

III. Backsheet Coating: Silicone Provides Long-Lasting UV Protection for the Module

(1) Protective Requirements for Photovoltaic Module Backsheets

The backsheet of a photovoltaic module is a critical component that protects the internal solar cells; it is directly exposed to outdoor conditions and must withstand prolonged, intense ultraviolet radiation. If the backsheet’s UV resistance is inadequate, its coating may age, chalk, or delaminate, thereby losing its protective function. As a result, the underlying solar cells are subjected to UV exposure, leading to degradation and a significant reduction in the module’s service life.

(2) UV-Resistant Advantages and Applications of Organosilicon Backsheet Coatings

Thanks to its outstanding UV resistance, silicone is widely used as a coating material for the backsheet of photovoltaic modules. It is applied to the surface of the backsheet substrate via a specialized process, forming a dense and stable protective layer. Its key advantages are as follows:

First, it exhibits exceptional resistance to UV-induced degradation, effectively absorbing and reflecting ultraviolet radiation to minimize radiative damage to the backsheet substrate and internal solar cells, thereby preventing aging phenomena such as yellowing, chalking, and delamination of the coating. Second, it boasts excellent weatherability and protective performance: its surface contact angle exceeds 100°, indicating strong hydrophobicity that resists water absorption and dust adhesion; moreover, it can withstand erosion from outdoor industrial emissions and weak acidic or alkaline environments, making it suitable for a wide range of photovoltaic power plant applications. Third, it offers excellent processability and compatibility, with superior light transmittance that allows coating thickness and performance to be tailored to specific requirements without compromising module light-absorption efficiency; additionally, it bonds firmly to the backsheet substrate, ensuring robust adhesion and resistance to delamination.

In practical applications, photovoltaic modules with silicone backsheet coatings maintain excellent appearance and protective performance even after prolonged outdoor exposure to ultraviolet radiation, reducing module power degradation by more than 40%. This effectively extends the service life of the modules and lowers the operation and maintenance costs of photovoltaic power plants.

IV. Comprehensive Advantages and Industrial Value of Organosilicon

The application of silicone in the sealing of photovoltaic modules and in backsheet coatings not only leverages its outstanding UV resistance but also benefits from its excellent overall compatibility. Silicone can be compounded and modified with materials such as glass fibers, ceramic powders, and flame retardants, thereby retaining its core UV-resistant properties while further enhancing the adhesive strength of sealants, the mechanical strength of coatings, and their flame-retardant performance, thus meeting the diverse operational requirements of photovoltaic modules across different applications.

Meanwhile, silicone materials are solvent-free, halogen-free, and environmentally friendly, complying with international environmental standards such as RoHS and REACH, thereby aligning with the green development trend of the photovoltaic industry. As the PV sector transitions toward higher efficiency and longer service life, high-efficiency cell technologies like TOPCon and HJT are gradually becoming mainstream, placing increasingly stringent demands on the protective performance of PV modules. Silicone materials have thus emerged as the core materials for module encapsulation and backsheet coatings, effectively strengthening the module’s sealing barrier and enhancing the backsheet’s UV protection. This significantly reduces UV-induced damage to the modules, ensures their long-term efficient and stable operation, and provides reliable support for the scalable, high-quality development of the photovoltaic industry.