Fraunhofer ISE produces TOPCon solar cell with 24% efficiency

05 Jun 2024

...and JinkoSolar’s tandem perovskite-silicon solar cell achieves 33.2%.

The Fraunhofer Institute for Solar Energy Systems (ISE) has this week claimed to be the first European research institute to switch to producing large-area M10 silicon wafers.

And its TOPCon solar cell in this 182mm-edge format has achieved a conversion efficiency of 24.0 percent. This result was presented for the first time at the 20th Photovoltaic Technology Advisory Board Meeting of the ISE.

ISE noted, “The trend in the photovoltaic industry is towards ever larger solar cells: While wafers with an edge length of 156.75 mm accounted for 80 percent of the market in 2018, wafers with an edge length of 182 mm dominate the market today.”

Quadratic wafers of this size bear the trade name “M10”. Solar modules with a large cell format are not only superior in terms of manufacturing costs, but also in terms of performance and efficiency. Large photovoltaic companies have therefore focused their investments on large-area wafers, ISE contends.

ISE says it has “successfully transitioned to this format with the successful production of the large-format TOPCon solar cell (Tunnel Oxide Passivated Contact) within its PV Technology Evaluation Center”.

“We are very excited that we can now support our industrial partners in optimizing their production processes with this large-area wafer format or even in newly entering into the production of such solar cells,” said Sabrina Lohmüller. The physicist is deputy head of the Silicon and Perovskite-Silicon Tandem Solar Cells department and is also responsible for quality management at PV-TEC.

The highly efficient TOPCon cell architecture was originally developed at Fraunhofer ISE and was presented in 2013 for the first time demonstrating its record efficiency. In the past two years, production capacity of this cell type has been massively expanded worldwide. According to the International Roadmap Photovoltaics, published by the VDMA, TOPCon solar cells will have a market share of almost 50 percent by 2024.

120 µm-thin solar cell

The large-format TOPCon solar cell, which was presented to industry representatives and funding bodies at the PV Technology Advisory Board meeting in Freiburg, was processed entirely at ISE. The approximately 120 µm-thin solar cell was metallized with screen-printed contact fingers and calibrated at CalTeC at the Institute for Solar Energy Research in Hameln, Germany. Researchers at ISE also electroplate M10 solar cells with copper for metallization.

“Achieving an efficiency of 24.0% with the first batch suggests that we will exceed 25% with the next optimization steps. This recent success lays the foundation for our medium-term goal of large-area silicon-based tandem solar cells with an efficiency potential of well over 30 percent,” said Dr. Ralf Preu, director of the Photovoltaics Division at ISE.

JinkoSolar’s tandem perovskite-Si solar cell hits 33.2%

China-based Solar module manufacturer JinkoSolar (“Jinko”) has announced a “significant breakthrough” in the development of its N-type TOPCon-based perovskite tandem solar cell. Tested by the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, the cell achieved a conversion efficiency of 33.24%. The perovskite tandem solar cell employs Jinko's n-type monocrystalline TOPCon solar cell as the bottom cell.

This level of conversion efficiency for the perovskite/TOPCon tandem solar cell has been achieved through various materials and technology innovations including ultra-thin poly-silicon passivated contact technology, novel light-trapping technology, intermediate recombination layer with high light transmittance and high carrier mobility, and efficient surface passivation technology using hybrid materials.

The company stated, “This achievement demonstrates the compatibility of TOPCon as a mainstream solar cell technology with the next-generation perovskite/silicon tandem cell technology, breaking the efficiency limit of single-junction silicon solar cell.”

Jinko says it invests substantial R&D annually for technological innovation. To date, the company has applied for over 3,800 global patents and has been granted more than 3,500, providing higher efficiency and better value energy solutions to the global solar photovoltaic market.

Dr. Jin Hao, CTO, commented, “This milestone lays a solid technical foundation for the company’s continuous development. We believe that, as we continue to deepen our scientific research and technology, we will contribute to building a greener and more sustainable new energy structure.”