The Backsheet is a vital component of a solar PV module, (commonly referred to as a solar panel). It serves as the outermost layer on the ground-facing side or the bottom of the panel.
The function of a Backsheet
A solar Backsheet is typically made from a polymer or a combination of polymers.
It plays a crucial role in the longevity and performance of the PV module by protecting the Encapsulant layer adjacent to it and the PV cells from ultraviolet (UV) radiation, moisture penetration, and external elements such as wind, dust, sand, and chemicals.
The Backsheet also acts safeguards the electrical components of a solar module by providing insulation and ensures the structural integrity of the module.
Key properties of an ideal Backsheet
Not all Backsheets are created equal.
To ensure the longevity and reliability of a module during its expected lifespan of 25 years, the Backsheet must possess three critical properties:
Weatherability: Ability to withstand external environmental conditions. This includes aspects such as a low moisture vapor transmission rate, preventing the entry of undesirable UV rays, etc.
Mechanical strength: Aids in maintaining the structural integrity of the modules by withstanding high-speed winds, snow load, etc.
Adhesion: Binds with the Encapsulant while reflecting some of the light that has passed through the PV cells.
These properties are essential for maintaining optimal performance and protecting the module from environmental and operational stressors.
Therefore, when choosing a PV Backsheet supplier, it is vital to inquire about how they achieve a consistent, optimal balance between these properties.
What happens if the Backsheet fails?
The Backsheet is an integral part of the module, so a defect or failure usually has a detrimental impact on the performance and longevity of the PV module.
Some common problems associated with defective or failed Backsheets include significant power degradation, mechanical failure, and safety-related failures that include arcing and can lead to the module catching fire.
Detecting these faults at an early stage can be challenging since the Backsheet is typically hidden from view. Generally, when failures in the Backsheet material occur, then happen en masse, meaning that multiple modules may be affected at the same time.
In larger PV systems, even a major failure and leakage current may go unnoticed due to the limited sensitivity range of fault detection components.
In conclusion, the Backsheet has a significant role to play in all aspects of a module’s performance. While module manufacturers are responsible for selecting high-quality backsheets from reputable suppliers, end customers (those who install solar panels on their homes, offices, or parks) should also be able to assess the quality of backsheets to ensure they are investing in the right solar power system.
Image credits:
RenewSys
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