European Patent Office removes major legal barrier for solar module production in Europe

European Patent Office decision

The European Patent Office (EPO) has revoked patent EP4092759B1, removing a major legal barrier for European manufacturers using modern multi-busbar (MBB) cell technologies in crystalline silicon solar modules. This decision follows an opposition procedure supported by the European Solar Manufacturing Council (ESMC) and a consortium of European photovoltaic (PV) manufacturers and research institutes.

Background of the revoked patent

The patent concerned key aspects of multi-busbar interconnection techniques, which are now among the most common approaches in contemporary solar module production. Originally owned by Korea’s LG Electronics and later acquired by China-based JA Solar, the patent attempted to secure protection for technical features that had already become standard practice in the industry.

Multi-busbar technology in Europe

Multi-busbar features have been publicly known, documented, and widely used for more than a decade in PV manufacturing. These MBB techniques were pioneered in Europe in the early 2010s and have since evolved into a global standard for solar module interconnection.

Almost all European module producers now rely on round-wire MBB architectures to improve performance and reduce costs. The approach helps reduce shading losses, lower electrical resistance, decrease silver consumption, and ensure durable long-term electrical connections within the module.

Legal challenge and EPO procedure

The opposition against the patent was filed on 30 October 2024 by ESMC together with a group of European companies and research organisations, working with an intellectual property law firm. The opponents argued that the divisional patent introduced subject matter that went beyond the parent application, making the grant legally invalid as “added matter” under European patent law.

An oral hearing took place on 15 October 2025 after extensive written exchanges, counter-arguments, and preliminary opinions between the parties and the EPO. At the end of this full-day session, the EPO’s Opposition Division decided to revoke the patent in its entirety, without needing to further examine novelty or inventive step.

Impact on European PV manufacturers

The revocation safeguards open access to essential PV manufacturing techniques that underpin a large share of current European solar module production. It is described as good news for efforts to re-establish and expand the European solar PV industry, which has been facing intense competition from manufacturers in Asia.

ESMC notes that, had this patent remained in force, many European module manufacturers using MBB cells could have faced infringement risks despite relying on long-established technologies. Removing this legal uncertainty is seen as crucial for enabling companies to invest in new capacity without fear of unjustified patent claims.

Statements from ESMC

Christoph Podewils, Secretary General of the ESMC, emphasized that the patent tried to cover aspects that had already been industry standards for a long period. He warned that maintaining the patent could have put the vast majority of European module makers using MBB cells at risk of infringement actions.

According to Podewils, the outcome reinforces Europe’s capability to scale up PV manufacturing free from unwarranted patent barriers. He added that open access to established MBB techniques is vital for ensuring a level playing field and strengthening the competitiveness of the European solar manufacturing sector.

Next steps and potential appeal

The party that lost the opposition case retains the right to appeal the EPO’s decision. The deadline for filing a notice of appeal is 7 January 2026, and detailed grounds for appeal would need to be submitted by 7 March 2026.

Until any possible appeal is filed and decided, the current revocation removes an important source of legal uncertainty for module manufacturers using MBB technologies in Europe. Industry stakeholders see this as an opportunity to proceed with investment and expansion plans under clearer patent conditions.

“This outcome strengthens Europe’s ability to scale up PV manufacturing without facing unjustified patent barriers. Ensuring open access to established MBB technologies is essential for creating a level playing field and supporting the industry’s competitiveness.”

Author’s summary

The EPO’s revocation of a controversial multi-busbar patent lifts a key legal risk for European solar module makers, supporting open access to standard MBB techniques and improving conditions for scaling domestic PV manufacturing.

European Solar Manufacturing Council (ESMC) — 2025-11-29