1.What are the core functions of traditional rigid crystalline silicon photovoltaic modules?
Excellent weather resistance: Resists UV radiation, high temperatures, humidity, and thermal cycling.
Extremely high insulation: Ensures the safety of the module's high-voltage system.
Good moisture barrier properties: Prevents moisture intrusion that could corrode the cells and internal circuitry.
Mechanical strength and tear resistance.
Lightweight design and cost balance.
2.What are the mainstream types of multilayer composite thin film materials?
Classic structure: PET (polyester film, providing insulation and strength) sandwiched between two layers of weather-resistant film (such as PVF fluoropolymer film or PVDF coating).
Development trend: Using perfluorinated materials, polyolefin materials, etc.
3.What are the shortcomings of standard color-coated coils compared to standard color-coated coils?
Insufficient insulation: The metal substrate is a conductor and cannot meet the high insulation safety requirements of the backsheet.
Heavy weight: Much heavier than polymer film backsheets.
Long-term weather resistance challenges: Although the front coating has good weather resistance, the back coating (back paint) usually has lower standards. Long-term exposure to ultraviolet light, high temperature and high humidity may lead to aging, chalking and other problems, affecting the protection of the solar cells.
Moisture barrier properties: Relying on the coating, there may be weak points such as pinholes, making it less reliable than multilayer composite films.
Different processing methods: Traditional module backsheets are bonded to the solar cells through a lamination process, which is not suitable for color-coated coils.
4.What are the specific application scenarios of color-coated steel coils in the photovoltaic field?
Building Integrated Photovoltaics (BIPV) Roofing/Wall Substrate
This is the largest and most mature application of pre-coated steel coils in the photovoltaic field. Pre-coated steel coils serve as building envelope materials (such as roof panels and wall panels), on which photovoltaic modules are directly integrated or installed.
In this case, the pre-coated steel coil plays the role of "structural support and waterproof enclosure," rather than the "backsheet" of the module itself. It needs to be bonded to photovoltaic modules (such as flexible thin-film modules or standard modules) through structural adhesives, clamps, etc.
Flexible/Lightweight Photovoltaic Module Substrate or Backsheet
This is currently the most relevant and exploratory direction. Some new flexible photovoltaic technologies (such as CIGS thin-film and perovskite modules) require more robust and lower-cost flexible substrates.
Technology Variants: Using extremely thin (e.g., 0.1-0.3mm) aluminized zinc-coated steel sheets or stainless steel strips as substrates, and depositing photovoltaic functional layers on them, finally coating the outermost layer with a high-performance weather-resistant protective coating. This can be seen as an "upgrade and specialized application of the pre-coated steel coil technology concept."
Advantages: The metal substrate offers excellent strength, moisture barrier properties (zero water permeability), fire resistance, and weather resistance, making it ideal for metal roofing, vehicle roofs, etc.
Key: The "coating" here is no longer ordinary polyester or PVDF, but a multi-layered composite coating system that may integrate insulation, functional, and protective layers.
5.What are the conclusions and trends?
Clear Distinctions:
Traditional Crystalline Silicon Modules: Backsheet = Polymer Composite Film, does not use standard color-coated coils.
BIPV Enclosure Systems: Substrate/Roof = Color-coated coils, supporting the photovoltaic modules.
New Flexible Modules: Substrate/Backsheet = Specially Designed Thin Metal Strip + Special Coating, can be seen as a high-end evolution of color-coated coil technology.
Trends:
With the development of BIPV and lightweight, flexible photovoltaics, the technology route using thin metal strips as a substrate, combined with high-performance functional coatings, is gaining attention. This product is similar to color-coated coils in appearance and some processes, but its technical requirements (insulation, weather resistance, adhesion to the cell layers) are far higher than ordinary building-grade color-coated coils.