Qcells plans to open a gigawatt-scale factory producing tandem perovskite-silicon solar panels in 2029, a date that would put one of the world's largest panel manufacturers ahead of most Western rivals in the race to commercialize the technology. Global Chief Technology Officer Danielle Merfeld told Canary Media that the company is already testing full-size tandem panels in the field.

The announcement matters because no manufacturer currently mass produces tandem panels with a commercial warranty comparable to conventional solar. Perovskite layers paired with silicon cells have set record efficiencies in laboratories, but the materials degrade too quickly in real-world conditions. That gap between laboratory performance and bankable product is the whole problem.

Qcells brings unusual resources to it. The company, a German firm before South Korea's Hanwha acquired it out of bankruptcy for nearly $45 million in 2012, has developed tandem cells since 2016. It opened a pilot research line for tandem prototypes in Germany in 2022, then launched a 40-megawatt pilot line in South Korea in 2024 that produces full-size tandem panels. Competing perovskite startups — Tandem PV, Oxford PV, Caelux — remain largely at smaller test-cell scale.

The pilot capacity itself is a marker. Forty megawatts of full-size panel production is a different discipline from record-setting sample cells.

What does the efficiency record mean?

Current high-performance panels convert sunlight at roughly 24% efficiency, a figure that has improved by about half a percentage point annually over the past decade, according to Merfeld. In 2024, an independent body confirmed a Qcells tandem record of 28.6% for a standard-size silicon cell layered with perovskites.

That single result equals roughly eight years of incremental silicon progress at the historical rate. Conventional panels will narrow the gap somewhat by 2029, but Merfeld expects a further cycle of process improvements once tandem production reaches mass scale.

For project economics, the appeal is straightforward. Tandem panels produce more energy in the same footprint, or the same energy in a smaller one, with compounded savings on wiring, auxiliary equipment, land and labor — the non-panel costs that dominate system prices.

Why does an incumbent think it can win?

Silicon Valley has bet billions that venture-backed startups are best placed to invent new climate hardware. Qcells proposes the opposite 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."

The company has spent years studying the degradation mechanisms — light, heat, dampness — that erode silicon cells over time. "We have the right muscles to solve those problems," Merfeld said.

In July, Qcells announced its tandem panel passed testing against quality standards set by UL and the International Electrotechnical Commission, enduring calibrated physical stresses while still producing power reliably. Since no tandem panel has operated for twenty-plus years, these accelerated degradation tests serve as the proof point banks will need before financing installations.

The evidence file remains incomplete. Qcells declined to disclose its perovskite ingredient formulation or degradation data from early field testing. The company has installed tandem panels at its own test sites over the past year and is shipping units to potential customers for evaluation. The 2029 timeline allows room to convince large buyers before committing gigawatt-scale capital.

Where will the factory go?

The location is undecided, though a company presentation in Seoul last week appeared to indicate Jincheon, South Korea, as the pick. Qcells designed its vertically integrated factory in Cartersville, Georgia, to upgrade to tandem fabrication when the time comes, Merfeld noted.

Industrial policy will be a determining factor, she argued. Qcells has previously pushed for U.S. domestic manufacturing incentives and trade protections against cheap imports from China-linked firms. The company's own history explains the position: Germany's "Solar Valley" collapsed in the early 2010s under competition from state-backed Chinese manufacturers, and Qcells survived only through the Hanwha purchase.

"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."

How competitive is the field?

The race is tightening. China's GCL said it opened a 1-gigawatt tandem factory in Kunshan, near Shanghai, last year — though Chinese factory developers draw on direct public support unavailable elsewhere, which limits what the project proves about commercial readiness. In the United States, Tandem PV is targeting 2028 for a gigawatt-scale factory. "I think we've seen enough on the product side. It's more you've got to raise money," CEO Scott Wharton told Canary Media.

That comment captures the structural difference. The startups must prove the product and raise the capital. Qcells must prove that an incumbent multinational can out-innovate smaller, singularly focused competitors — a feat the energy sector has not often staged.

The next milestones are legible: the factory site decision, further third-party degradation data, and the first bank-financed tandem installations. Until banks sign off, 28.6% remains a laboratory number with a factory date attached.