Fraunhofer ISE & Oxford PV Achieve 25% Tandem Module Efficiency

• Fraunhofer ISE and Oxford PV have announced 25% efficiency for silicon-perovskite tandem solar module
• Using Oxford PV cells, they achieved the highest output of 421 W on an area of 1.68 sq. m.
• The team now aims to secure a certification of the PV module manufactured on Module-TEC mass production equipment of Fraunhofer ISE  

German solar research institution Fraunhofer Institute for Solar Energy Systems ISE has announced the 'world's most efficient' silicon-perovskite tandem solar module in the industrial format. It has achieved 25% efficiency for the module manufactured using perovskite-silicon tandem solar cells from Oxford PV.

It also achieved the highest power output of 421 W on an area of 1.68 sq. m. using Oxford PV's perovskite silicon solar cells in M6 format with an efficiency of 26.8%.

Perovskite-silicon tandem cells are believed to have a theoretical efficiency potential of over 43%, compared to less than 30% for silicon solar cells. Currently, the commercially available solar module with the highest efficiency on TaiyangNews Top Solar Modules Listing has 24% efficiency and involves back contact cells (see Top Solar Modules Listing—January 2024).

The Head of Photovoltaics at Fraunhofer ISE Prof. Dr. Stefan Glunz said, "This makes it more efficient than any silicon PV module in industrial format that has ever been built. The fact that technologies compatible with mass production were used for its production demonstrates the enormous potential of tandem technology for the PV industry."

Using Oxford PV cells, Fraunhofer ISE manufactured a glass-glass PV module with 25% efficiency using its mass production equipment Module-TEC. The team developed low-temperature processes for interconnecting and encapsulating solar cells that are suitable for industrial mass production.

It used a new multispectral solar simulator to determine the efficiency of tandem PV modules. This can work when both cell layers are illuminated by different LED light sources under the conditions under which they would produce electricity in natural sunlight. The method was additionally validated with outdoor measurements as the current standardized measurement methods cannot be completely transferred to this new technology.

Fraunhofer ISE along with Oxford PV are now aiming to secure a certification of the PV module alongside conducting intensive tests for long-term stability at the former's climate chambers of the TestLab PV Module.

Oxford PV is rolling out its perovskite cells in a small series at its Brandenburg factory, and plans to start commercial production of tandem solar cells in 2024.

"This new world record is a key milestone for Oxford PV and proves that our tandem solar cells can deliver record-breaking performance when assembled into solar modules," said Oxford PV CEO David Ward.

Speaking at the TaiyangNews High Efficiency Solar Technologies Conference in December 2023, China's GCL Perovskite shared the company's silicon-perovskite tandem module efficiency roadmap. GCL Perovskite's Chairman of the Board Fan Bin said in 2024 the company will target a tandem efficiency of 26% for the 2m x 1m module, exceeding 27% in 2025 on a 2.4m x 1.2m size (see XBC & Next Gen: High Efficiency Solar Technologies Conference Day 4).