On February 7, 2025, Shanghai Jinko Green Energy Enterprise Management Company, Limited and Zhejiang Jinko Solar Company (collectively “Jinko”) sued Waaree Solar Americas Incorporated and Waaree Energies Limited (collectively “Waaree”), alleging Waaree’s “solar panels, including its TOPCON N-type solar panels, use Jinko’s patented technology without authorization.” Shanghai Jinko Green Energy Enter. Mgmt. Co., Ltd. v. Waaree Solar Ams. Inc., Case No. 4:25-cv-00532, Dkt. No. 1 (Complaint) at ¶ 14 (S.D. Tex. Feb. 7, 2025).
According to the complaint, “Jinko is a globally leading photovoltaic (PV) module (‘solar panel’) manufacturer and energy storage system integrator” that “holds the leading position for the N-type TOPCon segment with annual module shipments reaching 48.4 GW in 2023.” Jinko v. Waaree, Dkt. No. 1 at ¶¶ 5, 7. The complaint alleges that Waaree “supplies solar modules in the United States for use in residential and commercial buildings and solar utility projects,” and that Waaree’s products include “N Type TOPCON solar modules.” Id. at ¶ 10.
Jinko asserts infringement of US Patent No. 11,824,136 (“the ’136 patent”), titled “Solar Cell, Manufacturing Method Thereof, and Photovoltaic Module,” which it asserts is directed to TOPCon solar cells. According to the ’136 patent, TOPCon solar cells rely on “a ‘tunnel effect’ to passivate the rear surface. An existing TOPCon solar cell rear surface structure sequentially includes a semiconductor substrate, a tunnel oxide layer, a doped conductive layer and a passivation layer on the rear surface from the inside out.” The ’136 patent, 5:3-7.
Jinko claims its invention includes “matching between texture structures on substrate surfaces,” which “can improve an open-circuit voltage of the solar cell, reduce contact resistance of a metal electrode, and improve conversion efficiency of the solar cell.” The ’136 patent, 1:43-47.
Jinko presents an embodiment of its TOPCon solar cell with texture structures 11, 12:
The ’136 patent, Fig. 1 (annotations added).
The ’136 patent discloses that the second texture structure 11 includes a pyramid-shaped microstructure 111 that “may be formed by texturing the semiconductor substrate.” This pyramid-shaped microstructure “enables a metal paste to better fill the microstructure when the metal paste forms an electrode by screen printing, which obtains better electrode contact, can effectively reduce series resistance of the solar cell, and improves the fill factor.” The ’136 patent, 6:4-18.
The ’136 patent, Fig. 2 (annotations added).
The ’136 patent also discloses that “the first texture structure 12 includes two or more first substructures 121 at least partially stacked on one another. The first texture structure 12 presents a non-pyramid-shaped microstructure profile.” The ’136 patent, 7:41-48.
The ’136 patent, Fig. 3 (annotations added).
According to the ’136 patent, by controlling the “distance between the substructures in the first texture structure,” the roughness of the real surface of the semiconductor substrate can be ensured to stay within an appropriate range, which leads to the following purported benefits:
Helps to improve the uniformity of the tunnel oxide layer formed on the first texture structure, ensure better performance of the tunnel oxide layer formed, further inhibit a high local doping concentration of the doped conductive layer, reduce contact resistivity, improve the open-circuit voltage of the solar cell, and improve a fill factor and photoelectric conversion efficiency.
The ’136 patent, 24:65-25:9.
Claim 1 of the ’136 patent recites:
A solar cell, comprising:
a semiconductor substrate, wherein a rear surface of the semiconductor substrate has a first texture structure, the first texture structure has a non-pyramid-shaped microstructure and includes two or more first substructures at least partially stacked on one another, a top surface of the first substructure is a polygonal plane, and a one-dimensional size of the top surface of the outermost first substructure is less than or equal to 45 μm; and wherein a front surface of the semiconductor substrate has a second texture structure, the second texture structure includes a pyramid-shaped microstructure, the pyramid-shaped microstructure includes a top portion away from the front surface of the semiconductor substrate and a bottom portion close to the front surface of the semiconductor substrate, and in a direction away from the front surface and perpendicular to the front surface, a distance between the top portion and the bottom portion of the pyramid-shaped microstructure is less than or equal to 5 μm;
a first passivation layer located on the second texture structure of the front surface of the semiconductor substrate;
a tunnel oxide layer located on the first texture structure of the rear surface of the semiconductor substrate;
a doped conductive layer located on a surface of the tunnel oxide layer; and
a second passivation layer located on a surface of the doped conductive layer.
Jinko lists as accused products over fifty of Waaree’s “TOPCON N-type solar module series,” and provides a claim chart comparing Waaree’s BiN-08-580 model against the limitations in claim 1 of the ’136 patent. Jinko v. Waaree, Dkt. No. 1 at ¶ 24 (identifying accused products); id. at Ex. 2 (infringement chart).
Jinko v. Waaree, Dkt. No. 1, Ex. 2 (Infringement Chart) at 3 (annotations in original) (purporting to illustrate Waaree’s BiN-08-580 model).
Jinko alleges the BiN-08-580 model includes, among other limitations, the recited first texture structure and second texture structure:
Jinko v. Waaree, Dkt. No. 1, Ex. 2 at 5 (annotations in original) (purporting to illustrate BiN-08-580’s alleged first texture structure).
Jinko v. Waaree, Dkt. No. 1, Ex. 2 at 7 (annotations in original) (purporting to illustrate BiN-08-580’s alleged second texture structure).