Solar PV technology trends: A shift towards Polyolefin encapsulant
Photovoltaic (PV) modules are made up of several components, including the encapsulant layer that surrounds the solar cells and protects them from the external environment. The most commonly used encapsulant material is ethylene-vinyl acetate (EVA), which is known for its low cost and ease of use. However, EVA has some drawbacks, such as being prone to acetic acid corrosion and rear-side potential induced degradation (PID). These limitations have led to the development of a new type of encapsulant material known as polyolefin.
Polyolefin encapsulant has been shown to reduce the risk of acetic acid corrosion and rear-side PID compared to EVA. This is especially relevant for glass-glass type constructions, where the encapsulant layer is exposed to more moisture and oxygen. Polyolefin encapsulant is also more resistant to ultraviolet (UV) radiation, which can cause yellowing and degradation of EVA over time.
Despite the benefits of polyolefin encapsulant, there are also some risks associated with its use. For one, it is around 10% more expensive than EVA and has slightly lower light transmission efficiency (about 0.25%). Additionally, cost-reduction methods may introduce new manufacturing processes that could affect the encapsulant’s performance. For example, different encapsulant types at the front and back of the cell might introduce new, unknown failure modes.
Another risk associated with polyolefin encapsulant is the possible difficulties in controlling the thickness and uniformity of thin polyolefin layers in co-extruded encapsulants. This can affect the module’s overall performance and durability. There may also be process changes necessary, such as longer manufacturing times and narrower control windows for temperature, which can increase manufacturing costs.
Finally, the long-term durability of polyolefin encapsulant is still unknown. It often takes 10-20 years of data to discover issues with new materials, and this is true for polyolefin encapsulant as well. Therefore, while it has some promising benefits, more research is needed to fully understand the long-term durability of this new encapsulant material.
In conclusion, polyolefin encapsulant has shown some benefits over traditional EVA encapsulant in terms of reducing the risk of acetic acid corrosion and rear-side PID. However, it is more expensive, has lower light transmission efficiency, and there are risks associated with introducing new manufacturing processes. Therefore, it is important to carefully consider the benefits and risks before choosing a module encapsulant material.