Recently, at the Quality Month — Supply Chain Value Win-Win Co-Creation and Sharing Event hosted by Tongwei Solar, Gokin Solar stood out from numerous participating projects with its “Concentric Circle Breakthrough Improvement” project, winning the first prize in the competition and claiming the highest honor at this Co-Creation and Sharing Event. This award is not only an authoritative certification of Gokin’s quality management capabilities, but also another fruitful result of Gokin and Tongwei advancing together and achieving win-win value.
Facing the Pain Point: A Minor Material Anomaly Exposes a Major Issue
In recent years, against the backdrop that wafer costs account for a limited share of cell costs, the concentric circle issue has become a major quality pain point constraining TOPCon cell yield. Facing this industry-wide challenge, with the coaching and support of the Tongwei Solar platform quality team, Gokin Solar formed a cross-departmental task force led by its Quality Director and set improvement targets around the concentric circle issue:
Be the first to achieve “zero” concentric circles under EL conditions, challenging the industry iron law that TOPCon cells “inevitably produce concentric circles”;
Maintain a stable concentric circle proportion of <0.05% in mass supply;
Reach the industry’s first-tier level, with zero batch anomalies.
Scientific Breakthrough: The “Three-Step Method” Cracks the Quality Code
The project team distilled the “Gokin Three-Step Anomaly Analysis Method”: first, use the FMEA tool to identify the key stages where anomalies occur; second, use the 5Why method to dig deep into root causes at those key stages; third, by reducing occurrence frequency and detection ratings, use regression analysis, experimental simulation, correlation analysis, and other methods to formulate countermeasures.
For the three key AP=H anomaly stages—vacuum gauge distortion, incomplete oxygen poka-yoke rules, and outdated oxygen standards—the team tackled them one by one:
Vacuum gauge distortion: established equipment calibration standards and management processes, and formulated a quarterly comprehensive calibration mechanism;
Incomplete oxygen poka-yoke rules: through extensive data research, the team used regression analysis to precisely locate the “oxygen inflection point,” pioneering the monocrystalline industry’s “Gk dynamic alternating oxygen content detection poka-yoke solution”;
Outdated oxygen standards: opened up the closed loop of “customer service follow-up — product analysis — quality execution — continuous monitoring,” responding immediately to customer-side standard changes.
Abundant Results: Breaking the Industry’s Iron Law, Achieving Win-Win Value
Through the joint efforts of both teams, the project’s established goals were achieved on schedule:
Be the first to achieve an industry breakthrough of “zero” concentric circles for TOPCon cells, with the zero-concentric-circle batch achievement rate reaching 14.9%;
Lead outstanding peers across all dimensions of concentric circle performance, breaking the “iron law” that TOPCon cells will always produce concentric circles;
Gokin became the first manufacturer in the industry to introduce the FMEA tool into the wafer stage.
From a gap to gradual leadership, this process reflects the two teams’ continuously deepening understanding of the product. Going forward, Gokin looks forward to further deepening synergy with Tongwei, continuously promoting the standardized implementation of improvement projects, deepening the application of FMEA tools, further enhancing product consistency, and using data interconnection to achieve ultimate cost reduction, ultimate efficiency improvement, and ultimate quality improvement.
