TECHNICAL ARTICLE

Black G10 and FR4 for PV Backsheets

2021-10-29 12:12  |  By: ZTELEC  |  181click

Fiberglass reinforced plastic (FRP for short) typified by G10 and FR4 is widely used in the national economy. Today let’s discuss its application in renewable energy sector——FRP solar module (aka silicon photovoltaic module).

First, we’ll get to know the structure of PV module to understand better the material selection and function of each part. The PV module is mainly divided into five layers from the top to the bottom: tempered glass, EVA, PV cells, EVA, and the PV backsheet are stacked up in order, pumped into vacuum and hot pressed, then bonded together to be a finished PV module.

structure of PV module

1. Tempered glass is used in the right side of the PV module, being a support for the whole module to provide enough mechanic strength. The Fe content in tempered glass for the PV industry should not exceed 0.02% otherwise the glass will turn green when viewed from the side way.

2. Ethylene Vinyl Acetate (abbreviated to EVA), a thermoplastic resin, is the main encapsulant for battery pack encapsulation. It’s used on both sides of the battery pack when stacked up. In the lamination process, EVA can fill in the whole battery pack, protecting the PV module.

3. The PV battery pack: single pieces of photovoltaic cells are welded and connected in series to be the PV cell strings, which are further connected with bus bar to be the battery pack.

4. EVA: this layer of EVA is bonded to the solar backsheet.

5. PV backsheets, used on the reverse side of PV module for providing outer layer strength support for the module, are required to have excellent weather resistance for protecting the PV cells, metallic contact and encapsulating materials from the water vapor and moisture as well as voltage resistance and insulation. Quality PV backsheets guarantee 25 years of product life or longer in harsh environments.

FRP Materials for PV backsheets are required to have the following main properties:

black G10/FR4

①  Tensile strength and gluten extensibility.

②  Thermal resistance and low hot shrinkage rate ensure that the backsheets withstand high temperature in a long time.

③  Good water-proof properties.

④  Voltage resistance.

⑤  High peel strength ensures that backsheets are bonded well with EVA.

According to the metrics mentioned above, black G10 and FR4 can be selected as the PV backsheets. The black backsheet is the best color match for the all-black PV module. The sheets, if coated with a film, can increase the reflectance and power output of the PV module. FR4, added with flame retardancy, is an improvement for G10. Both are made from electronic alkali-free fiberglass cloth impregnated with epoxy resin matrix by hot pressing technology. Good mechanical and electrical properties allow G10 and FR4 as PV backsheets to provide moisture resistance, insulation, and support for PV module. Black G10 and FR4 produced by ZTelec Group can be cut to the size required by customers.

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