PTAB

IPR2025-00859

JinkoSolar Co Ltd v. LONGi Green Energy Technology Co Ltd

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Solar Battery Module and Manufacturing Method Thereof
  • Brief Description: The ’214 patent describes solar battery modules designed to reduce resistive losses and improve efficiency. The invention involves using rectangular solar cells, connecting them in a specific series-parallel configuration, and matching the number of parallel cell strings (n) to the cell’s long-side-to-short-side aspect ratio (n:1).

3. Grounds for Unpatentability

Ground 1: Obviousness over Boretz and Maehane - Claims 1-5, 8, and 11 are obvious over Boretz in view of Maehane.

  • Prior Art Relied Upon: Boretz (a 1971 NASA technical report) and Maehane (Japanese Application # H07-106619).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Boretz disclosed the core inventive concept of the ’214 patent. Specifically, Boretz taught a solar array module using rectangular solar cells with a 1/2:1 short-to-long side ratio (where n=2) arranged in two parallel columns of serially connected cells (where n=2), thus meeting the key limitation of independent claim 1. Boretz also disclosed front-to-back interconnectors, cell strings, and the series-parallel array structure. Petitioner contended that while Boretz disclosed the array configuration, it did not detail the electrode structure on the cells. Maehane was asserted to supply this missing element by teaching a conventional electrode design with light-receiving surface bus electrodes parallel to the short side of the rectangular cell and corresponding rear-surface electrodes, as well as symmetrical electrode placement (for claims 3 and 4) and electrode-free margins (for claim 5).
    • Motivation to Combine: A POSITA would combine these references to implement a known, industry-standard electrode configuration (from Maehane) into the solar module of Boretz. This combination would predictably improve current collection and connection efficiency, which is a well-understood goal in solar module design.
    • Expectation of Success: Petitioner asserted a high expectation of success, as combining a known solar module layout with a standard electrode structure was a routine and predictable improvement to enhance electrical performance.

Ground 2: Obviousness over Zhang and Ravi328 - Claims 1-4, 6, 8, and 11 are obvious over Zhang in view of Ravi328.

  • Prior Art Relied Upon: Zhang (Chinese Application # CN 201171051 Y) and Ravi328 (Indian Application # 1328/KOL/2007).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued this combination provided an alternative path to obviousness. Zhang disclosed a photovoltaic module with cells arranged in a series-parallel configuration, including series groups connected in parallel. However, Zhang used square cells. Ravi328 was asserted to teach the use of rectangular half-cut cells (with a 1/2:1 aspect ratio, where n=2) derived from standard 125mm square wafers. Ravi328 also disclosed the claimed electrode structure, including busbars parallel to the rectangular cell's short side and symmetrical placement. Petitioner argued that modifying Zhang's module to use Ravi328's half-cut cells would result in the configuration claimed in claim 1, where two columns (n=2) of cell strings are connected in parallel. Ravi328's disclosure of creating half-cut cells by laser-cutting full square cells was also argued to render claim 6 obvious.
    • Motivation to Combine: A POSITA would combine Zhang and Ravi328 to improve the performance of Zhang's module. The benefits of using half-cut cells to reduce resistive losses and boost overall module efficiency were well-known, and Ravi328 provided an explicit teaching of this technique. A POSITA would have been motivated to apply this known efficiency-improving technique to Zhang's basic series-parallel module design.
    • Expectation of Success: Petitioner argued success would be reasonably expected because incorporating half-cut cells to minimize resistive losses was a common, well-understood, and predictable improvement in the field of solar module design at the time of the invention.

Ground 3: Obviousness over Boretz, Maehane, and Krishnamurthy - Claims 9 and 10 are obvious over Boretz and Maehane in view of Krishnamurthy.

  • Prior Art Relied Upon: Boretz, Maehane, and Krishnamurthy (a 2008 publication on CubeSat design).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built upon the Boretz and Maehane combination from Ground 1. For the additional limitations of claims 9 and 10, which require cells with asymmetrically chamfered corners arranged in a specific orientation, Petitioner relied on Krishnamurthy. Krishnamurthy was asserted to teach rectangular solar cells where only one long side has chamfered corners. It also allegedly disclosed arranging these cells in a string such that the chamfered edge of one cell does not face the non-chamfered edge of the adjacent cell.
    • Motivation to Combine: A POSITA would incorporate Krishnamurthy's chamfered cell design into the Boretz/Maehane module to maximize the utilization of the module area and simplify automated assembly. Using cells cut from pseudo-square wafers (which have chamfered corners) is a common manufacturing practice to reduce silicon waste, and Krishnamurthy's specific arrangement was one of a finite number of predictable layout choices.
    • Expectation of Success: Petitioner argued for a reasonable expectation of success, as applying a common cell shape (chamfered half-cell) and a simple, tessellating arrangement to a known module design was a predictable modification to optimize manufacturing and layout efficiency.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including:

    • Boretz, Maehane, and Ravi328 for claim 6 (dividing a square cell).
    • Boretz, Maehane, and Ravi260 for claim 7 (continuous string connector).
    • Zhang, Ravi328, and Fujii for claim 5 (electrode-free margins).
    • Zhang, Ravi328, and Ravi260 for claim 7 (continuous string connector).
    • Zhang, Ravi328, and Krishnamurthy for claims 9 and 10 (asymmetrically chamfered cells).

4. Relief Requested

  • Petitioner requests institution of inter partes review and cancellation of claims 1-11 of the ’214 patent as unpatentable.