Borealis is an $8 billion revenue Austrian plastics company looking to serve the future perovskite market with its thermoplastic polyolefin (TPO) encapsulant. The special angle here is that the thermoplastic only needs low process temperatures, similar to those in perovskite manufacturing. We spoke to Geir Kristian Johnsen, Program Manager for Renewable Energy in the New Business Development department of Borealis.
Degradation is one of the most important technical hurdles for perovskites to become a viable product. Degradation may even be the single most important challenge of all alongside large form-factor, scaled-up manufacturing processes, and power output per square meter. Within degradation, encapsulation and edge seals are going to be crucial. Perovskite is a lot more fragile than silicon, so the products developed by Borealis and others may play a significant role in the pace of growth for the new photovoltaic semiconductor as a whole.
Perovskite modules may never rival the 30-year-plus T80 (80% performance after 30 years) of silicon technology, and a wide range of market-viable products can be figured out for which a mere 10-year lifespan is more than enough (devices, satellites, and so on) – but broadly speaking, the nascent perovskite industry wants to reach a 20-year lifespan.
The middle of this article provides general context on Borealis and the evolution of the silicon solar industry’s encapsulant choices, and will return to the perovskite topic later on.
Borealis is already a world leader on insulation for high-voltage cabling – playing a big role in the 8 GW German Corridors transmission initiative to link North Sea wind to Bavarian industrial demand centres, for example. The company is the second-biggest polyolefin producer in Europe.
Borealis plans to reach 100% renewable energy in 2030 at its operations – no mean feat given that chemicals production is an energy-intensive industry, so much so that a good fraction of it has died off in countries like Germany and the UK since the 2022 sanctions. Another renewable agenda for the company is its ‘circular cascade’ concept, featuring renewable feedstock, CCUS product, and products made using feedstock sourced from mechanical and chemical recycling.
Circular plastics are a big project since in packaging, if you have a plastic that has polyolefins layered with other plastics, it’s impractical to recycle. Developing recyclable mono-materials that have the necessary strength and other characteristics is a big research project. Today, solar encapsulant material can be produced from up to 65% non-fossil-fuel feedstock.
Anyway – for photovoltaic modules, Borealis’ original strategy was polypropylene backsheet material. This was a superior product in terms of performance – easy to protect against ultraviolet radiation, not sensitive to moisture, no need for a fluorine layer to guard against PFAS leakage (as with Polyethylene terephthalate (PET) backsheet) – but it was more expensive to produce, and thus lost out and got discontinued.
Today, like with just about all forms of renewable energy equipment across multiple industries, polymeric backsheets are sold at rock-bottom prices that may even be below cost of production, due to China’s production capacity across the solar supply chain varying from 150% to 200% of global demand.
So Borealis’ pricier polypropylene can only return to the scene if there are more stringent recycling standards introduced – to create a quite different situation from the $100 per kW China glut of 2024. If you burn standard (fluorinated) backsheets today, you produce some hydrofluoric acid, which is a problem for recycling. Another possible ‘in’ would be a renewed emphasis on module quality.
So Borealis’ pricier polypropylene can only return to the scene if there are restrictions placed on the standard Chinese products, perhaps in the form of stringent recycling standards. That would create a quite different situation from the $100 per kW Chinese solar module glut of 2024. If you burn standard backsheets today, you produce some hydrofluoric acid, which is a problem for recycling.
One problem with ethylene vinyl acetate (EVA), which still has significant market share in the industry today, is acetic acid formation when old and wet – which in turn degrades module components. That in turn limits its use in glass-glass modules (which are growing in market share) as these lack the backsheet permeability which would allow the acid to leak out. What broke EVA’s dominance was the adoption of Mono PERC bifacial since 2018, with polyolefin elastomer needed to mitigate the new problem of potential induced degradation (PID) thanks to its better electric isolation properties.
After Mono PERC solar cells came N-type cells, including heterojunction and its high sensitivity to moisture – which further played to POE’s strengths. TOPCon technology is also more fragile than PERC.
To return to the perovskite topic, as Geir Kristian Johnsen states, “the central rule of solar is that the cost per Watt must come down – and at this point, the best way to do that is to increase the Watts with tandem modules, or reduce the cost with Single-junction perovskite. And that’s how the learning curve of solar can continue.”
“Perovskite is a funny animal – even more fragile than all of the other cell types – it doesn’t like oxygen, it doesn’t like moisture it doesn’t like light which is kind of funny for a solar panel (referring to UV degradation risk). These things are finnicky – perovskite developers need to develop a cell with enough efficiency and durability on the lab bench scale, then they need to make it big enough for mass production potential – and then finally they need to encapsulate it into a module that they can sell.”
“Most companies are in the first and second steps, but a few companies are in the third step, and have publicly announced the building of factories, such as Microquanta, GCL and Utmolight. So at the moment perovskite commercialization is not a done deal – but one thing is clear, perovskite is sensitive and needs protection.”
“And most important for us, perovskite degrades under heat – you need to keep temperature low when laminating it. Crosslinking EVA and POE as is currently standard for silicon involves extruding a film with active reactants inside, a peroxide to trigger crosslinking, plus silane elements to enhance adhesion to the glass – when temperature goes to 150 degrees in the laminator.”
And there’s the main appeal of Borealis’ ‘Quentys’ range of encapsulant materials –avoiding 150-degree lamination temperature, as well as avoiding peroxide chemicals near the fragile perovskite layer, via thermoplastic adoption. This is on top of getting rid of crosslinking.
“That’s why you need a thermoplastic for perovskite” states Johnsen. “In theory that can be done just above melting point, though in practice for an industrial process it would need to be a bit higher. So now there’s a need for our Borealis ‘Quentys’ product, which allows for lamination at 110 degrees. Some scientists even request 100 degrees or lower.”
Johnsen points out that few perovskite companies have yet reached module assembly – but most of those who are, are interested. “The perovskite scene is nowhere near settled, while we try to follow what the perovskite industry wants from encapsulation. We control the polymerisation of the raw material for the encapsulant film, so we have a lot of flexibility on final product – we can go in a high-purity direction where further downstream suppliers work with mixtures of off-the-shelf products. We’ve done a lot of testing with our product on silicon over the years – it can survive a lot.”
Besides the main question of process temperatures, EVA also has to be avoided for perovskite because acetic acid formation would be especially severe for perovskite – multiple layers in a perovskite cell are particularly fragile in the face of that sort of degradation vector. The single-layer, no-crosslink nature of thermoplastic would make final modules easier to recycle – more useful for perovskites with their shorter lifespans.
Asked if solar encapsulation was one of the more difficult encapsulations Borealis Group does, Johnsen replied, “It’s certainly one of the most technical. There’s adhesion, there’s electrical insulation, many different requirements – it’s very complex, but we’re involved in food packaging and healthcare too, where requirements are also complex. You can find specific requirements in all kinds of industries – and so far polyolefins are the best cost vs performance material we’ve come up in a long range of applications.”
In other solar news
A 600 MW wind, 400 MW solar complex with 1 GW / 4 GWh battery energy storage has begun construction at Zhangye City, China, with a total investment of $1.3 billion. This is part of the ‘third batch’ of national large-scale wind-solar complexes, the policy which has expanded China’s renewable energy additions several times over in recent years.
Another such ‘third batch’ desert megaproject in Xinjiang, China is a $14 billion complex including 4 GW wind, 8.5 GW solar, 4 GW coal, 2.5 GW battery energy storage, which began construction in late September. And yet another is a 1.3 GW solar farm beginning construction in Yecheng County of Xinjiang with a $770 million investment.
Aiko Solar has raised $300 million to support a 10 GW cell-module solar factory.
Shichuang Energy will invest $30 million in a 1 GW ‘stacked-grid’ module factory. Stacked-grid is an upcoming design which improves metallization (reducing silver paste usage) via cell-string layout. In this case, and likely in general, this is using TOPCon technology.
First Solar has opened a new $1.1 billion, 3.5 GW factory in Lawrence County, Alabama, bringing the company’s global production capacity to 21 GW, of which 11 GW in the US. Those figures are set to reach 25 GW and 14 GW by end-2026.
Maharashtra State Electricity Distribution Company Limited (MSEDCL) has obtained permission from the Electricity Regulatory Commission (MERC) of the same Indian state to hold a 5.991 GW distributed solar tender.
The Chinese region of Inner Mongolia plans to host 21.4 GW of ‘desertification control’ solar projects by 2025, also called sand fixation projects. By 2030 this will expand to 89 GW, covering 1,533 square kilometers, which is a little over twice the area of Singapore.
IRENA has reported a global average LCOE of $44 per MWh for utility-scale solar power, for the year of 2023, down 12% year-on-year.
The US state of New Mexico has expanded the scope of its community solar programme by 300 MW, to 500 MW.
New Mexico lawmakers have also approved up to $942 million taxable industrial bonds to support Ebon Solar’s proposed cell factory in the state.
Goldi Solar is to expand its module production capacity to 14 GW by middle of FY 2026, plus 4 GW cell production capacity by FY 2027. Another Indian manufacturer, Solex Energy, is to invest in 5 GW of solar cell production capacity, while Tata Power announces a new 2 GW module factory and Vikram Solar seeks funds for another 3 GW facility.
SEG Solar has broken ground on 5 GW of ingot-module vertically integrated TOPCon production capacity in Indonesia.
United Solar has secured $156 million in finance from Future Fund Oman to support development of its polysilicon factory in Oman. With a production capacity of 100,000 tons, the facility can support 40 GW of solar wafer production. Its estimated total investment cost of $1.6 billion would make it the same price as the scores of similar facilities built in 2022 and 2023 in China.
Turkey has applied solar anti-dumping tariffs to Malaysia, Thailand, Vietnam, Croatia and Jordan, while the Vietnamese Department of Trade Remedies states that four solar manufacturers have been exempted. The tariffs allege that substantively Chinese products are being shipped from the affected countries. In the US, the analogous policy has been pushed forward with the Department of Commerce (DoC) applying duties to Southeast Asian solar cells varying from 0.14% to 292.61% (from company to company) in the wake of its preliminary AD/CVD findings. The DoC noted that imports of cells and panels from Cambodia, Malaysia and Thailand all more than doubled from 2022 to 2023, while Vietnamese imports grew by almost 50%.
The European Commission has approved a $1.1 billion Portuguese manufacturing support scheme which covers solar, battery, wind, CCUS, electrolyzer, and heat pump equipment.
A 400 MW solar, 100 MW battery project has been proposed by Brockwell in the UK.
Clearway Energy Group has secured $665 million for a 300 MW solar, 200 MW storage project in Texas, while TotalEnergies has commissioned the 720 MW Danish Fields and 455 MW Cotton Woods projects in the state, each of which boast 225 MWh battery systems.
Ameresco has completed 587.5 kW floating solar project in the US state of Utah.
Solar Asia, a Pakistani solar manufacturer, has announced a 730-Watt heterojunction module with 23.5% efficiency, using Tongwei cells and Sonnex Energie design. Indian module maker Waaree has announced its own 730-Watt, also N-type, also likely using Chinese cells and certainly wafers.
Italian regional authorities have approved 5.1 GW of utility-scale solar in the first nine months of 2024.
The EU has funded a research project named Laperitivo, set to run through 2028, with the goal of manufacturing large-scale perovskite modules with 22% efficiency for opaque and 20% efficiency. The focus is on development of large-scale manufacturing techniques, and includes plans for a 200 MW pilot line.
China Huaneng Group has invested $14 million in its a perovskite manufacturing subsidiary, which previously made its first module in March 2021, and announced a MW-level ‘commercial scale’ ‘world-first’ perovskite factory as being commissioned in December 2023.