Qcells Clears Crucial Tandem Module Tests, Paving Path to Market

• Qcells’ perovskite-silicon tandem modules have passed IEC and UL stress tests, marking a major step toward commercial deployment of high-efficiency tandem solar technology.

Qcells has crossed a pivotal threshold in the race to commercialize tandem solar technology, confirming that its perovskite-on-silicon modules can meet the industry’s most demanding reliability standards. The company announced that prototype tandem panels from its R&D line in Bitterfeld-Wolfen, Germany, have successfully cleared the critical stress tests set by IEC 61215-2:2021 and UL 61215-2:2021, with results independently validated by TÜV Rheinland.

At the heart of the achievement is Qcells’ two-terminal architecture, which marries an in-house perovskite top cell with a silicon bottom cell based on the firm’s well-proven Q.ANTUM technology. The modules sailed through:

• UV preconditioning (15 kWh/m²)

• Thermal cycling (200 cycles)

• Humidity-freeze (10 cycles)

• Damp heat (1,000 hours)

—all without breaching tandem-specific power-measurement limits defined in IEC TS 60904-1-1.

“To our knowledge, no other tandem module has met these benchmarks under tandem-specific measurement rules,” said Danielle Merfeld, Global CTO at Qcells, who hailed the milestone as a “critical step toward commercial readiness.” Fabian Fertig, Head of Tandem R&D, added that every process used on the pilot line is scalable, positioning the technology for streamlined mass production.

Tandem cells layer a wide-bandgap perovskite absorber over conventional silicon, capturing more of the solar spectrum and promising efficiencies above 30 percent—far higher than today’s mainstream panels. Yet concerns about long-term stability have stalled large-scale deployment. By proving its design can withstand harsh UV exposure, temperature swings, and moisture, Qcells argues that the reliability hurdle is largely cleared.

The next phase will focus on scaling and cost. With the pilot line producing full-area M10 formats—compatible with modern module assembly lines—Qcells says its tandem devices are already aligned with manufacturing realities. Commercial rollout timelines were not disclosed, but the company framed the test results as a “groundwork-laying” moment for bringing tandem modules to rooftops and solar parks worldwide.

For an industry hungry for efficiency gains without sacrificing durability, Qcells’ breakthrough hints that tandem tech is edging from lab curiosity to bankable product—potentially reshaping the cost and performance curve of solar power in the years ahead.