Layering perovskites onto regular silicon panels unlocks higher efficiency. Qcells hopes to beat the competition to market by leveraging its legacy manufacturing skills.
Qcells, one of the most prolific solar manufacturers operating in the U.S., is staking a claim on the next generation of solar power.
Laboratory scientists have established that solar panels convert sunlight to electricity with much higher efficiency if traditional silicon cells are paired with layers of perovskites, a type of crystal that can be synthesized with a wide range of ingredients. These constructions have set stunning efficiency records in the lab, but break down far too quickly out in the real world.
A number of startups — including Tandem PV, Oxford PV, and Caelux — have been trying to solve this problem and commercialize these so-called tandem perovskite panels. But none of them are mass producing and selling tandem panels with a commercial warranty akin to conventional solar.
Qcells aims to be among the first to make that leap. Qcells is testing full-size tandem panels in the field and plans to open a gigawatt-scale factory to produce them in 2029, Global Chief Technology Officer Danielle Merfeld told Canary Media.
That means competition is heating up in the race to build large-scale perovskite solar factories, even as the contenders still must prove that their tandem products survive long enough to be commercially viable.
Chinese company GCL said it opened a 1-GW factory last year in Kunshan, near Shanghai; that said, factory developers in China can avail themselves of many types of direct public support that aren’t available to companies in other countries, making it hard to extrapolate lessons about perovskites’ commercial readiness. In the U.S., Tandem PV is targeting 2028 for building a gigawatt-scale factory, CEO Scott Wharton told Canary Media. “I think we’ve seen enough on the product side. It’s more you’ve got to raise money,” he said.
Qcells, originally a German firm that was acquired by South Korea’s Hanwha in 2012, has been developing tandem cells since 2016. It opened a pilot R&D line to make tandem prototypes in Germany in 2022, then, in 2024, launched a 40-megawatt pilot line in South Korea that produces full-size tandem panels. That sizing is notable in itself, as the competing perovskite startups are still transitioning from smaller test cells to bigger systems.
Current high-performance solar panels convert the sunlight with around 24% efficiency. That number has been inching higher as manufacturers hone their craft, Merfeld said: Over the last decade, the rate has improved by half a percentage point each year.
Qcells set a tandem efficiency record in 2024, when an independent body confirmed a rate of 28.6% for a standard-size silicon cell layered with perovskites. That’s like gaining eight years of incremental progress, instantly. Conventional panels will have narrowed the gap a bit by 2029, but Merfeld expects another cycle of process improvements once tandem hits mass production.
Should Qcells or any competitors succeed in bringing perovskites to market, that could profoundly accelerate the adoption of solar power, which has already become the top new power source getting built in the U.S. and around the world.
Tandem panels produce more energy in the same size package as conventional panels. That means installers could turn rooftops or fields into more productive clean power plants in the same footprint. Or they could generate the same amount of electricity in a smaller space, with compounded savings on all the non-panel costs, like wiring, auxiliary equipment, land, and labor.
Leapfrogging clean energy hardware is painstaking work fraught with setbacks — just ask anyone hoping to bring solid-state batteries to market, or actually install a small modular nuclear reactor. Silicon Valley has invested billions of dollars in the belief that nimble, venture-backed startups are best suited to invent these new climate solutions, rather than the ossified incumbent energy companies. Qcells proposes a different theory of the case.
“We’re not a startup, unlike a lot of the Western tandem developers,” Merfeld said. “We don’t need to raise money. We don’t need to excite investors, except for our own internal owners. We’re only working on commercial scale.”
In other words, setting new records with tiny sample cells might make sense if the goal is to generate headlines and stimulate venture capitalists, but that is a separate pursuit from honing a product for mass manufacturing.
Qcells has spent years studying the “killer issues” that degrade silicon cells over time, such as light, heat, and dampness. “We have the right muscles to solve those problems,” Merfeld said.
To that end, in July Qcells announced its tandem panel passed testing against the solar panel quality standards set by UL and the International Electrotechnical Commission. The panels had to withstand a barrage of highly calibrated physical stresses and still produce power reliably. Since no tandem panel has actually operated for 20-plus years, these third-party accelerated degradation tests offer a necessary proof point for the banks that will ultimately need to finance installations of the technology.
There’s more to do to keep building that confidence. Qcells declined to share the ingredients it chose for its perovskites, or to share degradation data from early field testing. But Merfeld said the company installed tandem panels at its own test sites over the last year, and is also getting them to potential customers so they can see for themselves how they work. Waiting until 2029 to launch the gigascale factory allows time to convince large buyers of solar panels that they should make the jump to perovskites.
The location of that proposed factory has not been decided yet (though a company presentation in Seoul last week seemed to indicate that Jincheon, South Korea, was the pick). Qcells designed its new, vertically integrated solar factory in Cartersville, Georgia, to easily upgrade to tandem fabrication when the time comes, Merfeld noted.
But Merfeld argued that supportive industrial policy will be a determining factor in where the tandem factory goes. Qcells has previously advocated for domestic manufacturing incentives and trade protections against cheap imports from China-linked firms, to bolster U.S. solar manufacturing as a strategic industry. The company suffered from the absence of such policies in Germany, which let that country’s “Solar Valley” get wiped out by competition from state-backed Chinese manufacturers in the early 2010s. (Qcells survived that episode because Hanwha bought it out of bankruptcy for nearly $45 million.)
“We learn by doing,” Merfeld said. “If you support the innovation here, you build that cycle that you need to build more and learn more.”
Qcells has far more experience scaling gigawatts of solar production than the rival perovskite startups. It just has to demonstrate that an incumbent multinational corporation can beat its smaller, singularly focused competitors in the innovation game.
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Julian Spector is a senior reporter at Canary Media. He reports on batteries, long-duration energy storage, low-carbon hydrogen, and clean energy breakthroughs around the world.