PTAB

IPR2025-00187

Mundra Solar PV Ltd v. Trina Solar Co Ltd

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Solar Cell and Method for Manufacturing the Same
  • Brief Description: The ’009 patent discloses a solar cell featuring a tunnel oxide passivated contact (TOPCon) structure, which includes a polysilicon back surface field (BSF) layer and an underlying tunnel oxide layer. The central inventive concept asserted during prosecution was an "isolation portion" located at the periphery of the cell's back surface, which excludes the oxide and polysilicon layers to prevent electrical shorting.

3. Grounds for Unpatentability

Ground 1: Obviousness over Jin and Feldmann - Claims 1-8, 11-13, 15, and 17 are obvious over Jin in view of Feldmann.

  • Prior Art Relied Upon: Jin (Application # 2013/0056051) and Feldmann (a 2014 scientific paper titled "Passivated rear contacts for high-efficiency n-type Si solar cells...").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Jin disclosed a conventional bifacial solar cell with all the basic elements of claim 1 except for the specific TOPCon structure (a polysilicon BSF over a tunnel oxide layer). Critically, Jin taught the use of an isolation gap ("gap T") at the periphery of the back surface to prevent the BSF from short-circuiting with the emitter. Feldmann, in turn, explicitly taught replacing a conventional diffused BSF with a high-efficiency TOPCon structure to reduce surface recombination. Petitioner contended that combining these references would result in Jin's solar cell structure, including its isolation gap, but with Feldmann's improved TOPCon BSF, thereby meeting all limitations of the independent claim.
    • Motivation to Combine (for 35 U.S.C. §103 grounds): A person of ordinary skill in the art (POSITA) would combine the references as a simple substitution of a known, superior component for an older one to achieve a predictable improvement. A POSITA would have been motivated to replace Jin's less efficient diffused BSF with Feldmann's well-documented, high-performance TOPCon structure to improve the overall efficiency of Jin's solar cell design.
    • Expectation of Success (for §103 grounds): A POSITA would have had a high expectation of success, as the combination involved applying a known technique (Feldmann's TOPCon BSF) to a known device (Jin's solar cell) to obtain the predictable result of improved performance without affecting the function of Jin's isolation gap.

Ground 2: Obviousness over Chang and Jin - Claims 1-8, 11-13, and 15-17 are obvious over Chang in view of Jin.

  • Prior Art Relied Upon: Chang (Application # 2014/0299187) and Jin (Application # 2013/0056051).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Chang disclosed a bifacial solar cell that already combined the key features of the ’009 patent: a TOPCon structure on the back surface and an explicit teaching of an "isolation region" or "periphery region" where the TOPCon layers are not formed. Petitioner argued that Chang teaches every limitation of the claims. Jin was cited to provide additional, well-understood implementation details for the isolation region that Chang described but did not illustrate in detail, such as the passivation film covering the isolation region.
    • Motivation to Combine (for §103 grounds): The motivation was framed as a POSITA looking to implement the isolation region taught by Chang. A POSITA would have looked to analogous art, such as Jin (which shares a common original assignee with Chang), to understand the conventional and necessary details of forming such a region and ensuring it is passivated to prevent recombination losses. This was not modifying Chang's invention but simply applying known techniques to realize it.
    • Expectation of Success (for §103 grounds): A POSITA would have had a clear expectation of success in applying Jin's straightforward method for creating an isolation gap to the device already described by Chang, as it was a standard technique for a known problem.

  • Additional Grounds: Petitioner asserted additional obviousness challenges for claims 9, 10, 14, and 16 by adding tertiary references to the primary combinations. These included adding Seo (Patent 8,647,914) for teaching passivation layers on substrate side surfaces (claims 9-10), Watabe (Japanese Publication No. JP2010186862A) for teaching dual-layer bus bar electrodes for cost reduction (claim 14), and Chang for teaching specific layer thicknesses (claim 16).

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial would be inappropriate. Against denial under 35 U.S.C. §325(d), Petitioner contended that its asserted prior art combinations and arguments were not considered by the examiner during prosecution. Against denial under the Fintiv factors, Petitioner argued that the only parallel proceeding is at the ITC, which, according to a USPTO Director's memo, should not be a basis for denial. Petitioner also cited its expeditious filing after being served with the ITC complaint and the compelling merits of the petition as factors weighing heavily in favor of institution.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-17 of Patent 10,230,009 as unpatentable.