EPO Revokes Key Multi-Busbar Patent After ESMC Opposition, Removing Legal Threat For Nearly All European Solar Module Makers

The European Patent Office (EPO) has revoked a key patent related to multi-busbar (MBB) connections in solar modules, following an opposition initiated by the European Solar Manufacturing Council (ESMC) and a consortium of European PV manufacturers and research institutes. This decision removes a major legal obstacle that could have affected almost every module producer in Europe using modern MBB cell technology—technology that is considered an industry standard today. The patent in question, EP4092759B1, was originally owned by LG Electronics and later acquired by JA Solar.

According to Christoph Podewils, Secretary General of the ESMC, the patent attempted to cover techniques that have long been widely known and routinely used across the industry. He explained that if the patent had remained valid, most European manufacturers using MBB cells could have faced infringement risks even though they were relying on established and publicly documented technologies.

Multi-busbar technology has been a standard feature in solar module production for more than a decade. It was first developed in Europe in the early 2010s and has since become a widely adopted method for improving module performance. By using multiple round wires to collect current from the solar cell, MBB designs reduce shading, minimize resistance, lower silver usage, and create more durable electrical connections. These techniques are now part of nearly every crystalline-silicon module produced in Europe and beyond.

The revoked patent was a divisional patent based on an earlier European filing dating back to 2014. It claimed exclusive rights to solar cells featuring six or more busbars, the use of solder-coated round wires for interconnection, and solder pad structures designed for attaching those wires. The opposition team argued that the patent extended beyond the technical information disclosed in the original parent application, making it legally invalid. This argument focused on “added matter,” a key requirement in European patent law that ensures new patents do not introduce content not supported by earlier filings.

The EPO accepted these arguments, leading to a full revocation of the patent without needing to assess whether the technology was new or inventive. The decision followed a lengthy process involving the exchange of documents and legal arguments, culminating in an oral hearing on 15 October 2025. At the end of the session, the EPO’s Opposition Division confirmed that the patent would be revoked entirely. This outcome is important for Europe’s efforts to rebuild its solar manufacturing sector.

By eliminating a patent that could have restricted the use of standard interconnection technology, the decision provides greater legal certainty for companies operating in the region. It supports fair competition and ensures that established MBB techniques remain accessible to all manufacturers. Podewils stated that this ruling will help the European PV industry scale up production without the threat of unjustified patent claims that could hinder growth. The party that lost the case has the right to appeal. Any such appeal must be filed by 7 January 2026, with detailed grounds for the appeal submitted by 7 March 2026.