What’s the truth behind the ill-fated AAA backsheet? What are the facts about polyamides? How much can we really trust historical field data claims? Are fluropolymers really needed for backsheet durability? Your questions answered…
The B series of DSM Endurance backsheets have an additional weather-exposed PA12 outerlayer, for extra protection against extreme weather conditions. PA12, is a special type of polyamide, known for its excellent weatherability. The core of our backsheet is a polyolefin. Our backsheet is classified as a so-called “APE” backsheet.
In 2010, Isovoltaic engineered a full polyamide backsheet, a so-called AAA backsheet, based on co-extrusion.. However the material system was particularly poorly designed, with glass-fiber in the core layer, that resulted in extreme anisotropic properties causing weakness and cracking in TD. It ended in failure with modules losing performance in the field, the product being withdrawn, and Isovoltaic going bankrupt.
The industry is still counting the cost of this failure. The truth is that in responsible and knowledgeable hands, both the use of polyamides and the co-extrusion process itself are effective and proven for use in backsheets – and especially in DSM Endurance backsheets.
At DSM we have a 50-plus year track record in materials science. We know a thing or two about polyamides – and there’s no doubt that they are excellent materials for PV applications – in the right hands.
A material like polyamide 12 isn’t just proven to perform in solar applications; it has been the material of choice for applications in the automotive, aviation and energy industries for many years thanks to its proven physical, chemical and mechanical reliability in harsh environments. Polyamide 12 is exceptionally resistant to UV, abrasion, and moisture – which makes it ideal for protecting modules in extreme desert and tropical climates. In fact, this innovation received the 2019 TÜV Rheinland All Quality Matters award for best desert application.
How valid is field test data stretching back 10, 20 and perhaps even 30 years? While the individual PV backsheets in question may well have performed for this period, there is one glaring problem: the materials used to manufacture that same brand or model will have almost certainly changed in the intervening years.
In the quest for ‘zero-margin’ backsheet design we’ve seen a culture develop where the Bill of Materials is being exchanged for lower cost or more readily available materials. So the reality is that field data stretching back 10, 20 and even perhaps 30 years are of little value, because many backsheets being produced today are different from their predecessors.
The short answer is no. The protective fluoropolymer outer film has halved in thickness from more than 40 to less than 20 microns for most fluoro-based backsheets on the market today. In some cases, the outer ‘protective layer’ is now little more than a polymer coating just around 10microns thick. In most cases, the fluoropolymer inner layer has entirely disappeared and been replaced by a non-fluoropolymer film or coating. Even the layer known as ‘f-layer’ - which should create the impression that fluor is still present - no longer in practice contains fluoropolymers.
And discover how we can help you boost solar power.