Cracking of the PV Backsheet in Solar Panels
The Backsheet is the outermost layer of a solar panel or PV module. It provides mechanical strength and protection from environmental stresses like heat, moisture, and dust.
A PV Backsheet is a multilayer laminate designed to perform specialized functions.
The primary functions of the innermost or PV Cell facing adhesion with the encapsulant reflecting the sunlight back to the cells and blocking UV lights from reaching other layers of the Backsheet and preventing them from prolonged degradation / damaging.
The outermost layer or air-side layer of the Backsheet comprises PVDF/PVF or HPET layers that are designed to withstand the harsh climate, and additionally, in the case of PVDF/PVF airside Backsheets, they add flame retardancy to the PV Module, while keeping the dust and moisture out.
Several instances of Backsheet material failures, especially cracking has been witnessed in China, India, America, and the Mediterranean region.
The widespread nature of this failure strongly indicates that there is no clear correlation between cracking and climatic conditions, as cracking of these Backsheets was observed in hot-arid, hot-humid, cold, and temperate weather conditions.
When this external layer cracks it results in swifter degradation of the PV Cells of the solar panel along with insufficient insulation. This ultimately causes PV plants to go into huge losses as their output starts dropping, along with a high risk of other failures occurring.
Deeper Backsheet cracks may lead to Backsheet delamination i.e the separation of the layers that make up the Backsheet.
Factors causing Cracks in the Backsheet can be mentioned below:
1. Inferior-quality raw materials lead to:
Poor Hydrolytic properties - hydrolytic degradation/cracking
UV Degradation - UV degradation, yellowing, browning, cracking
Poor Moisture Barrier causing underperformance of PV solar cells
2. Poor Backsheet design/construction
3. Defective or substandard manufacturing processes, and protocol
4. Incompatible thermal expansion co-efficient Backsheet / Frame / Encapsulant etc. expand and contract top different extents under the same conditions
Why worry if you have a warranty for your solar panel?
A key function that Backsheets perform is fire retardancy. A compromised Backsheet means a higher risk of your home or solar project catching fire!
Most installers source a large number of PV modules from a single source. And in turn, module manufacturers order large Backsheet rolls. This means that a faulty Backsheet will impact a large number of modules in one go. This means replacing a huge number of modules and till the replacement process and reinstallation is completed, little or no generation may be possible from the affected modules.
How does RenewSys ensure no cracking or Backsheet degradation?
RenewSys appoints its suppliers after rigorous testing of supplied samples. The downward value stream is also well-controlled to diminish the probability of failures at our customer's plants.
We carry out periodic quality checks apart from incoming material testing at our PV Backsheet manufacturing plant, as well as extensive accelerated environmental testing at our PV module manufacturing facilities to ensure that the quality of raw material meets specifications and performance expectations.
Additionally, to make testing of these crucial raw materials accessible to all, RenewSys has also set up a dedicated, independently run Laboratory that specializes in testing PV Polymer components (Encapsulants & Backsheets) and their raw materials. This lab is the only one of its kind in India and is NABL certified.
Lastly, especially for module manufacturers buying Encapsulant & Backsheet from RenewSys, we also have an exclusive program called - RenewSys Doctor PV that allows them to test their PV modules and incoming raw materials.