Fraunhofer ISE Breaks 30% Barrier with Industrial TOPCon-Based Perovskite-Silicon Tandem Cell

Fraunhofer ISE has reached a major milestone in next-generation photovoltaics, demonstrating a 30.6% efficient perovskite-silicon tandem solar cell built on an industry-standard TOPCon bottom cell. The achievement confirms that high-efficiency tandem architectures can be realized using scalable, cost-effective industrial processes, rather than laboratory-only designs.

The research, conducted at the Fraunhofer Institute for Solar Energy Systems (ISE) in Germany, represents a critical step toward commercial deployment of tandem solar technology—long viewed as the most promising pathway beyond the efficiency limits of single-junction silicon cells.

Why This Result Matters for Industrial Solar Manufacturing

Until recently, many perovskite-silicon tandem demonstrations relied on heterojunction (HJT) bottom cells with highly specialized surfaces and complex fabrication steps. While effective in research settings, these approaches raise concerns around cost, throughput, and compatibility with existing production lines.

Fraunhofer ISE’s latest result challenges that assumption.

The team successfully integrated a perovskite top cell with a TOPCon silicon bottom cell featuring a standard textured front surface, commonly used in today’s mass-produced PV modules. Importantly, the TOPCon bottom cell demonstrated shunt resistivity comparable to heterojunction designs, confirming that electrical performance is not compromised when using an industrially mature architecture.

This finding strongly supports the feasibility of large-scale tandem cell manufacturing using existing TOPCon production infrastructure.

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Efficiency Above 30% with Lean Process Flow

According to lead author Mario Hanser, this is the first perovskite-silicon tandem device to combine:

• An industry-standard textured TOPCon bottom cell

• Excellent surface passivation

• Conversion efficiency exceeding 30%

“We have fabricated the first perovskite-silicon tandem device that integrates a TOPCon bottom cell with an industry-standard textured front surface, achieving an efficiency of over 30%,” Hanser explained.
“Demonstrating the compatibility of the TOPCon cell design and its lean process flow with perovskite-silicon tandem integration represents a significant step toward cost-effective mass production of industrial tandem solar cells.”

The emphasis on lean processing is particularly relevant for manufacturers seeking incremental upgrades rather than complete factory redesigns.

TOPCon + Perovskite: A Scalable Path Beyond Silicon Limits

TOPCon technology is already widely adopted as the next mainstream silicon cell architecture, offering higher efficiencies and better temperature performance than PERC. By proving that TOPCon can serve as a robust bottom cell for tandem devices, Fraunhofer ISE effectively bridges today’s industrial reality with tomorrow’s efficiency roadmap.

For the solar industry, this implies:

• Faster commercialization timelines for tandem PV

• Lower capex risk compared to HJT-based tandem approaches

• A realistic path to module efficiencies well beyond 25–26% at scale

As global PV markets increasingly focus on land efficiency, balance-of-system cost reduction, and high-yield generation, tandem cells built on proven industrial platforms could become a defining technology of the next decade.

Looking Ahead

While challenges remain—particularly around perovskite stability, encapsulation, and long-term reliability—Fraunhofer ISE’s result provides strong evidence that perovskite-silicon tandems are no longer confined to the lab.

With TOPCon already dominating new production lines worldwide, the combination of industrial compatibility and record-level efficiency positions tandem solar technology as one of the most credible next steps for large-scale photovoltaic innovation.

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