2021 was everything but boring in the field of backsheets and encapsulation. A positive note for this segment is a continued solar market growth – and several product innovations to address the module manufacturer’s needs. On the other hand, backsheets now have a true competitor in glass.
In the past, glass and backsheets rarely crossed paths as far as module making is concerned; and when they did, it was for a little piece of the PV cake called bifacial. But what used to be a small niche segment of PV has now become mainstream at close to 20% in 2020 – and is rapidly gaining ground, expected to reach a global market share of over 50% within this decade. Making a bifacial module involves a special encapsulation scheme and a transparent rear cover. The choice of glass was natural, but only until transparent backsheets were introduced a few years ago. After a slow start, these backsheets were in high demand in 2020, when glass prices started to shoot up. But backsheet makers were in for disappointment with the glass price rally lasting only briefly – and was basically solved after capacities were rapidly expanded. In short, technically speaking, transparent backsheets appear to have been evolved to be a reliable rear cover, while the major constraint remains – price, although todays difference to glass of only about 15% leaves hope for the polymer side (see Glass vs Transparent Backsheet).
The recent developments for PVDF, which owned over half of the market among different backsheet materials in 2020, were also not on the positive side for backsheets. During 2021, PVDF’s prices went north dramatically as it also attracted strong demand from the storage industry, which made the formerly low-cost material much less attractive for solar. In fact, the PVDF developments helped the ‘comeback’ of glass for the rear cover, but at the same time, this opened a window for other backsheet materials. With low-quality PVDF reportedly causing a number of reliability issues for module manufacturers, there have been complaints about the dominance of this material in the solar sector anyway (see Quick Rise In Backsheets Material Prices).
Among the configurations that have come to the forefront to take the place of PVDF based backsheets is CPC, which seems to be benefiting the most for the moment, but also Tedlar has regained popularity. The non-fluoropolymer segment is also seeing some traction; pure PE or PP based backsheets are superior when it comes to environmental concerns and recycling – a topic that is quickly gaining importance in Europe these days. However, it remains to be seen how quickly PVDF resin suppliers expand capacities to address solar’s demand. If available in large enough quantities, PVDF still has a cost advantage over its polymer peers.
In times of rising material prices, the pressure is high to find other ways of cost reduction – and there is indeed quite some activity. An interesting alternative to the current state of the art of making these polymer stacks is coextrusion. The manufacturer’s response, though, has been mixed so far. The first products based on all-PP based coextruded backsheets are expected to hit as soon as the end of the first half of 2022.
The high raw material prices are also affecting the encapsulation segment – here it is incumbent EVA for which prices have skyrocketed in 2021. Technologically, there is no revolution on the horizon in EVA developments, but high-reflective white EVA is increasingly preferred for the rear of a module. With the teething issues addressed, this material will take a big chunk of rear side encapsulation. There is also further notable development in the POE segment. POE is becoming the rear encapsulant of choice in bifacial modules, addressing the shortcomings of EVA, but it also brings up other concerns such as bubble formation, longer processing times and difficulties with the MBB layout. The coextruded EPE structure – a EVA sandwich with a POE layer in the middle – developed as an alternative to pure POE is gaining ground. The stack is expected to become the mainstream solution for rear side encapsulation of glass-glass bifacial modules. Unlike in backsheets, coextrusion is very much welcomed here. The same approach is also used to fuse transparent and white EVA to make it further process-friendly, especially when using larger and thin wafers (see A Few Lead The Encapsulation Segment).
While not new but perhaps overshadowed by EVA’s strong dominance, silicones for encapsulation are now trying a comeback with an interesting USP – very long reliability of around 50 years. The target market this time around is not mainstream applications but the still very small though emerging segment of BIPV. The logic is to match module life to that of other building components. What it holds for the future remains to be seen, but for sure the important field of backsheets and encapsulation as a key to reliable power generation with solar modules is not boring at all these days.
This is the conclusion part from TaiyangNews’ recent Market Survey on Backsheet and Encapsulation Materials, which can be downloaded for free here
During our different virtual conferences, we also covered the topic of backsheets and encapsulation, among others at our Reliable Module Design 2021 Conference and our Solar Innovations 2021 Conference with presentations from Jolywood, Coveme and Cybrid.