Canadian Solar, Inc. et al. v. Maxeon Solar Pte Ltd.

This case, IPR2024-01038, involves an Inter Partes Review (IPR) initiated by Canadian Solar, Inc. and Canadian Solar (USA), Inc. (collectively, "Canadian Solar") against Maxeon Solar Pte Ltd. ("Maxeon") before the Patent Trial and Appeal Board (PTAB) of the U.S. Patent and Trademark Office. Canadian Solar is a global renewable energy company based in Kitchener, Ontario, specializing in the manufacturing of solar photovoltaic (PV) modules, battery energy storage solutions, and the development of utility-scale solar projects, notably including N-type TOPCon solar cells. Maxeon, headquartered in Singapore, designs and manufactures Maxeon® and SunPower® brand solar panels and is known for its tunnel oxide passivated contact (TOPCon) solar cell technology. This IPR was filed as a defensive measure by Canadian Solar in response to a patent infringement lawsuit brought by Maxeon in the U.S. District Court for the Eastern District of Texas, accusing Canadian Solar's n-type TOPCon solar panels of infringing Maxeon's patents.

The sole patent at issue in this specific IPR (IPR2024-01038) is U.S. Patent 11,251,315. This patent is directed to solar cell fabrication techniques, specifically related to tunnel oxide passivated contact (TOPCon) solar photovoltaic module technology. The procedural posture of this case places it within the administrative review framework of the PTAB, a specialized body within the USPTO tasked with evaluating patent validity. The PTAB provides an alternative, often faster, and less costly venue compared to district court litigation for challenging patent claims, and its decisions can significantly influence parallel infringement proceedings.

This case is notable within the highly competitive solar energy industry, particularly given the market's shift towards more efficient N-type TOPCon solar cell technology. While Canadian Solar achieved broader victories in other related IPRs against Maxeon's patents, the Final Written Decision in IPR2024-01038, issued on 2026-04-06, resulted in a ruling against Canadian Solar for patent 11,251,315. The PTAB determined that Canadian Solar was unable to demonstrate by a preponderance of the evidence that the claims of U.S. Patent 11,251,315 were unpatentable, thereby upholding the validity of this specific Maxeon patent. The ongoing intellectual property disputes between these two major players highlight the intense competition and strategic use of patent challenges in the rapidly evolving solar technology sector. Maxeon Solar Pte Ltd. has also recently sought judicial management in Singapore due to financial pressures and issues with U.S. Customs and Border Protection detaining shipments.

Key Legal Developments and Outcome in IPR2024-01038

This Inter Partes Review (IPR) concerned U.S. Patent No. 11,251,315 B2, initiated by Canadian Solar, Inc. and Canadian Solar (USA), Inc. against Maxeon Solar Pte Ltd.

Filing & Initial Pleadings (IPR Petition)

• Petition Filing: On June 25, 2024, Canadian Solar, Inc. (Petitioner) filed a petition for Inter Partes Review, IPR2024-01038, challenging claims 10-15 of U.S. Patent No. 11,251,315 B2 owned by Maxeon Solar Pte. Ltd. (Patent Owner). Another related IPR, IPR2024-01194, was also filed by Canadian Solar challenging claims 16 and 19 of the same patent, and was later consolidated with IPR2024-01038.
• Background Litigation: This IPR was filed amidst a broader patent infringement lawsuit initiated by Maxeon against Canadian Solar around March 25, 2024, concerning TOPCon PV cell technology. The underlying district court case is Maxeon Solar Pte. Ltd. v. Canadian Solar, Inc., No. 2:2024cv00210 in the U.S. District Court for the Eastern District of Texas.

Pre-Institution Phase

• Maxeon Solar Pte. Ltd. filed Preliminary Responses to Canadian Solar's petitions. Canadian Solar subsequently filed Preliminary Replies, and Maxeon filed Preliminary Sur-replies.

Institution Decision

• On January 14, 2025, the Patent Trial and Appeal Board (PTAB) instituted an Inter Partes Review of claims 10-15 of U.S. Patent No. 11,251,315 B2 in IPR2024-01038.
• Separately, on January 24, 2025, the PTAB instituted an IPR of claims 16 and 19 in the consolidated IPR2024-01194.

Claim Construction (Markman)

• In IPR proceedings, the PTAB generally construes claim terms according to their plain and ordinary meaning as understood by a person of ordinary skill in the art at the time of the invention, in the context of the entire patent disclosure. This standard aligns with Phillips v. AWH Corp.

Parallel Proceedings and District Court Stays

• In the parallel district court litigation (Maxeon Solar Pte. Ltd. v. Canadian Solar, Inc., No. 2:2024cv00210), infringement allegations specifically pertaining to patent 11,251,315 B2 were dismissed with prejudice in the U.S. District Court for the Eastern District of Texas in early June 2025. Weeks later, a motion to stay the district court litigation pending Inter Partes Review was granted for the asserted claims across three patents, including 11,251,315 B2.

Final Written Decision and Outcome

• A Final Written Decision (FWD) for IPR2024-01038 (consolidated with IPR2024-01194) was issued by the PTAB on January 12, 2026.
• In this Final Written Decision, the PTAB determined that Canadian Solar, Inc. did not demonstrate by a preponderance of the evidence that claims 10–16 and 19 of U.S. Patent No. 11,251,315 B2 are unpatentable.
• Therefore, the PTAB upheld the patentability of the challenged claims of U.S. Patent No. 11,251,315 B2 in this IPR. This outcome indicates Maxeon's claims for this specific patent were affirmed by the PTAB. While some general press releases from Canadian Solar suggested a broader victory against Maxeon's patents, the specific FWD for IPR2024-01038 regarding patent 11,251,315 B2 concluded that the challenged claims were not shown to be unpatentable.

Final Disposition

• The IPR was terminated on April 6, 2026, following the issuance of the Final Written Decision and a subsequent Inter Partes Review Certificate. While other related IPRs in the broader dispute may have been appealed, the metadata for IPR2024-01038 itself indicates it was terminated after the Final Written Decision was issued.

Canadian Solar, Inc. and Canadian Solar (USA), Inc., the petitioners in IPR2024-01038, were represented by attorneys from Sidley Austin LLP and Gillam & Smith.

The counsel of record representing the plaintiff(s) include:

• Samuel N. Tiu

  • Role: Attorney for Petitioner (Lead Counsel based on multiple mentions in filings and news)
  • Firm: Sidley Austin LLP, Los Angeles, CA
  • Experience Note: Tiu is recognized for his work in intellectual property litigation, particularly in inter partes review proceedings before the PTAB, representing Canadian Solar in a decisive victory where all challenged claims were invalidated.

• Brooke Shanelle Boll

  • Role: Counsel
  • Firm: Sidley Austin LLP
  • Experience Note: Boll was part of the legal team from Sidley Austin that represented Canadian Solar in the U.S. solar panel infringement dispute against Maxeon, which resulted in the invalidation of all patents-in-suit.

• Leif E. Peterson, II

  • Role: Provisionally Recognized PTAB Attorney, Back-up Counsel.
  • Firm: Sidley Austin LLP
  • Experience Note: Peterson is a recognized PTAB attorney who has represented petitioners in IPR proceedings, including Canadian Solar in IPR2024-01038.

• Michael J. Bettinger

  • Role: Counsel
  • Firm: Sidley Austin LLP
  • Experience Note: Bettinger was part of the Sidley Austin team that secured a victory for Canadian Solar in the Maxeon dispute, leading to the invalidation of patents at issue.

• Melissa Richards Smith

  • Role: Counsel
  • Firm: Gillam & Smith, Marshall, TX (based on firm's primary office)
  • Experience Note: Smith was part of the legal team representing Canadian Solar in this U.S. solar panel infringement dispute, contributing to the successful invalidation of the asserted patents.

Maxeon Solar Pte Ltd. was represented by counsel from Vinson & Elkins LLP in IPR2024-01038. Additionally, in-house counsel for Maxeon is also noted in related patent matters.

The counsel of record for Maxeon Solar Pte Ltd. are:

• Eric J. Klein

  • Role: Lead Counsel
  • Firm: Vinson & Elkins LLP
  • Office Location: Dallas, TX
  • Experience Note: Eric Klein is a partner in the Intellectual Property group at Vinson & Elkins, focusing on patent litigation across various technologies.

• Jeffrey R. Swigart

  • Role: Back-Up Counsel
  • Firm: Vinson & Elkins LLP
  • Office Location: Tokyo, Japan
  • Experience Note: Jeffrey Swigart is a counsel in the Intellectual Property group at Vinson & Elkins, with experience in patent litigation and post-grant proceedings.

• Corbin J. Cessna

  • Role: Back-Up Counsel
  • Firm: Vinson & Elkins LLP
  • Office Location: Austin, TX
  • Experience Note: Corbin Cessna is an associate in the Intellectual Property group at Vinson & Elkins, specializing in patent litigation and other intellectual property disputes.

• Marc Robinson

  • Role: Associate General Counsel, Products and Technology (in-house)
  • Firm: Maxeon Solar Technologies, Ltd.
  • Experience Note: Marc Robinson is a registered patent attorney in the U.S. and oversees all intellectual property programs at Maxeon. He has authored articles on patents and solar technology.