Nowadays it is a trend to use films based on polyolefins as encapsulants in PV Panels because of their advantages in front of the use of traditional EVA. Market offers different brands and grades of polyolefins (PO), which leads us to ask ourselves which of those to use. NovoGenio is offering the Grade NovoSolar®PLX as a response to the needs of the Photovoltaic Market.

What are the main differences to take into account among NovoSolar®PLX and the rest of POs in Market?:

 Crosslinking PO

The main difference is if the PO has the capacity or not to crosslink, being NovoSolar®PLX a crosslinking PO.

 When a PO crosslinks, it increases its capacity as an electrical insulator. This feature is evaluated with the volumetric resistivity parameter. While EVA has a volumetric resistivity of (10¹⁴ - 10¹⁵) Ω·cm, a non-crosslinking PO has a volumetric resistivity of the order of 10¹⁶ Ω·cm, and a crosslinking one increases its volumetric resistivity up to an order of magnitude of 10¹⁷ Ω·cm. The major electrical isolation of PO increases the resistance of PV Panel to the failing PID effect.

Humidity Isolation

Another distinguishing feature between the PO and EVA is the major isolation to humidity of the former, improving the isolation of components at the PV Panel and increasing its resistance to the failing PID effect. The isolation to humidity is evaluated with parameter WVTR, which represents the water steam transmission through the Film at determined conditions. The WVTR of NovoSolar®PLX is one of the bests, among the POs supplied into the Market:

Adhesiveness

Unlike the other POs, which have an appearance with a marked pyramidal engraving, NovoSolar®PLX shows a structured face A (with a soft granulate) and face B with a smooth surface (but matt).

When laminating between glasses, NovoSolar®PLX has an homogeneous appearance, while if we laminate POs with pyramidal engraving between glasses, that does not disappear completely.

What consequences could be derived from the non-disappearance of pyramidal engraving?

The area of the PV Panel is irregular and heterogeneous in its laminating properties (adhesiveness, insulation,…) causing points where the adhesiveness is not good and may lead to premature de-laminations.

Non - Embossing Effect (Please, refer to the picture at this ArtiBlog)

Another consequence of such a marked pyramidal engraving is that the “effective” thickness of the Film is much less than the nominal thickness. To obtain the effective thickness of a Film, we cut and weigh a piece of Film of 10 x 10 cm, knowing its density (data that normally comes in the technical sheet of the product), we can calculate its thickness (thickness = mass / surface * density). Here we show some data measured at NovoGenio:

Shrinkage

Most PO Manufacturers report very low shrinkage values (usually < 5%). This is true provided that the shrinkage test is done on a hot surface without preventing the adhesion of the Film.

But, what happens if we allow the Film to shrink freely, preventing it from sticking to any surface?

At NovoGenio we performed the shrinkage test by immersing a piece of the 10 x 10 cm Film in a container with water at 100ºC, and the results obtained are as follows:

Therefore, NovoSolar®PLX is the PO at Market which has a smaller free schrinkage so far.

What are the consequences of the shrinkage of the PO Film?

The schrinkage of a Film when subject to temperature is nothing more than the manifestation of the internal tensions accumulated by the molecules during their manufacturing process. The stresses in the PO Film can cause premature de-laminations, movement of the PV Module components, etc.

We expect this new ArtiBlog is of your interest and as usual, you can share with us your opinion. With crosslinking NovoSolar®PLX made by NovoGenio, we would like to be part of the 3.0 Photovoltaics Era and beyond!