EPO revokes Hanwha’s key solar cell patent after 11-year opposition battle

The EPO Board of Appeal 3.4.03 has revoked Hanwha Solutions’ EP 2 220 689 in its entirety on the grounds of lack of inventive step (case ID: T1358/23). The decision brings to an end opposition proceedings lasting more than eleven years, which initially involved ten opponents and ultimately left only Norwegian competitor REC Solar to face the Korean patent holder.

Following the oral hearing earlier this week, the BoA decided to revoke EP 689 in full. A written decision is not yet available. Hanwha had defended the patent, which covers a solar cell with two surface-passivating dielectric layers on a silicon substrate designed to reduce efficiency losses and increase output. Before the revocation decision, the patent was due to expire in 2028.

Ten opponents at the start

At first instance ten parties had challenged the validity of EP 689 before the Opposition Division. However, over the course of the appeal proceedings, all other opponents either withdrew or did not appeal, leaving only REC Solar EMEA as the sole opponent facing Hanwha Solutions Corporation before the BoA.

Previously, the Opposition Division had upheld the patent in limited form. The opposition proceedings were delayed by the insolvency of the former patent proprietor, Solarworld Industries, which had acquired the patent from the original applicant, the German Institute for Solar Energy Research.

Consequently, the EPO temporarily suspended the proceedings and retroactively set aside the Opposition Division’s first decision. The new proprietor, Hanwha, lodged an appeal against this. Subsequently, the Legal Board of Appeal ruled in 2020 that the first-instance opposition proceedings were to be resumed (case ID: J0010/19-3.1.01).

Following oral proceedings in 2022, the Opposition Division then maintained the patent in a limited form, against which both the patent proprietor Hanwha and REC Solar lodged appeals. These have now resulted in the full revocation of the patent.

Hanwha had not claimed damages in the infringement proceedings, but had only sought an injunction, the destruction and the recall of the goods. The judgment was enforced only in part, insofar as it related to the recall. REC Solar is now free to claim the costs of the legal proceedings back from Hanwha.

A long-running dispute

The patent was central to a series of infringement proceedings that Hanwha has pursued across several jurisdictions over the past few years.

Hanwha had asserted EP 689 against several competitors, including REC, Longi Solar and Jinko Solar. In 2020, Düsseldorf Regional Court ruled that all three defendants had infringed the German part of EP 689 with their solar modules. The court granted Hanwha an injunction, a recall order and an order for the destruction of the infringing products, although REC’s main products, N-Peak and REC Alpha, were not affected. The Higher Regional Court Düsseldorf dismissed the appeal against the first-instance infringement judgment in 2024, thereby confirming Hanwha’s victory at the German infringement courts (case ID: I-2 U 30/20).

In parallel proceedings in the Netherlands, the Dutch courts also ruled in Hanwha’s favour. The Court of Appeal in The Hague upheld a cross-border injunction against Longi Netherlands in 2022 covering eleven European countries, based on EP 689. Furthermore, Hanwha asserted the patent in the US and Australia, where the courts ruled in favour of REC.

Parallel proceedings

In the US and Australia EP 689 has parallel designations. The Federal Court of Australia ruled in 2023 that several claims were not valid and REC did not infringe the patent.

The dispute between Hanwha and REC was not limited to EP 689. The parties also clashed over REC Solar’s own patent EP 3 017 520. The EPO Opposition Division revoked EP 520 in 2022 on the grounds of impermissible extension, without addressing issues of prior art or inventive step. Hanwha had been one of six opponents challenging that patent.

Experience in solar technology

Patent attorneys Robert Baier and Oswald Niederkofler of Samson & Partner represented Hanwha Solutions before the BoA. The team is experienced in solar technology, having also acted alongside lawyers from Bird & Bird for JingAo Solar in the dispute with Chint and Astroenergy. In-house counsel Jan Schrick from Hanwha Solutions Corporation also participated in the proceedings.

Whilst Maiwald filed the patent, the original patent owner, the German Institut für Solarenergieforschung (Institute for Solar Energy Research) initially relied on Petereins Schley in the opposition proceedings. The firm was also responsible for the change of ownership, first to Solarworld and, following its insolvency, to Hanwha Q-Cells.

In August 2020, Samson & Partner took over the EPO proceedings on behalf of Hanwha. They also acted on behalf of the patent owner in relation to technical matters throughout the parallel infringement proceedings in Germany, where they worked alongside lawyers from Hoyng ROKH Monegier. The latter coordinated Hanwha’s Europe-wide enforcement campaign on the litigation side, with Düsseldorf partner Martin Köhler leading the German proceedings and Theo Blomme heading the Dutch cases.

Patent attorneys Dirk Sieckmann and Matthias Borchert of the patent attorney firm Betten & Resch represented REC Solar. In the infringement proceedings at the Düsseldorf courts, REC instructed a Taylor Wessing team led by Christian Lederer and Jan Phillip Rektorschek, working alongside the patent attorneys from Betten & Resch.

The former Taylor Wessing partners have since left the firm to set up the boutique firm Pentarc with several other lawyers from Taylor Wessing. The team has experience in disputes relating to solar technology, having represented clients such as Chint and Astroenergy in a UPC dispute against JingAo Solar.