First Solar filed a patent infringement suit against JinkoSolar in the U.S. District Court for the District of Delaware on 2025-02-25 over U.S. Patent No. 9,130,074, which covers methods of manufacturing TOPCon crystalline-silicon photovoltaic cells [S1].
The '074 patent portfolio, inherited from First Solar's 2013 acquisition of TetraSun, has issued counterparts in the United States, Australia, Canada, China, the European Union, Hong Kong, Japan, Mexico, Malaysia, Singapore, South Korea, the UAE, and Vietnam, with validities extending to 2030 and beyond, plus pending applications in the EU, Japan, Hong Kong, the UAE, and Vietnam [S1].
Patent Geometry: What the '074 Suit Targets
The asserted '074 patent specifically claims methods of manufacturing tunnel-oxide passivated contact crystalline-silicon PV cells, not the cells as articles of manufacture, which shapes how licensees and downstream module assemblers structure their process flows [S1].
First Solar publicly previewed the enforcement campaign in July 2024 by announcing the launch of infringement investigations against several leading c-Si cell manufacturers; the February 2025 JinkoSolar filing was the first publicly named defendant [S1]. Executive Vice President, General Counsel and Secretary Jason Dymbort stated: "Given the responses we received from other solar cell manufacturers in connection with our infringement investigations, we believe we have a strong TOPCon technology patent portfolio" [S1].
For sourcing teams, the practical effect is jurisdiction-specific: a process-line running in the U.S., EU, Australia, Korea, or Japan sits inside the issued-patent perimeter, while manufacturing concentrated in jurisdictions still listed only as pending applications carries a different exposure profile [S1].
Field Degradation Numbers: 0.52%-1.48% First-Year Window
An outdoor empirical study run at a Xi'an test field from November 2023 through August 2025 measured 9 TOPCon, 4 BC, and 4 HJT modules under site extremes of 41.8 °C highs, -20 °C lows, 500-750 mm annual rainfall concentrated in summer-autumn, and roughly 1500 hours of annual sunshine [S2].
Three TOPCon modules recorded first-year degradation between 0.52% and 1.48%, all below the industry's commonly cited first-year threshold of 2.0%, while two BC modules came in at 2.27% and 2.38% and two HJT modules jumped to 4.02% and 4.30% over the same window [S2]. Six additional TOPCon units in supplementary testing showed 651-day degradation between 0.93% and 4.46%, with five of six clearing the "first-year ≤ 2.0%, subsequent annual ≤ 0.6%" expectation [S2].
BC units split: a 600 W unit at 1.34% degradation after 350 days stayed inside the limit, but a 455 W unit at 3.67% after 566 days overshot it; HJT modules on both follow-up retests exceeded 3% degradation, with low-temperature silver-paste durability under prolonged high-temperature, high-humidity exposure cited as the dominant failure driver [S2].
Cost Geometry: 6-9 fen/W Versus 0.015-0.02 yuan/kWh LCOE Spread
TOPCon modules priced 6-9 fen/W below BC and HJT equivalents at the sourcing layer, and 0.07 yuan/W lower than BC/HJT when accounting for bifacial gain, materially shifts BOS economics on the same site [S2].
For a 1 GW (DC) plant, that pricing gap alone means RMB 60-90 million of incremental module procurement spend if BC is selected instead of TOPCon; combined with the degradation curve, TOPCon LCOE lands 0.015-0.02 yuan/kWh below BC at typical Chinese grid-market clearing prices [S2].
China Photovoltaic Industry Association (CPIA) modelling shows a 1 GW plant whose average annual degradation rises from 0.7% to 1.0% loses 625 million kWh of cumulative 25-year generation, equivalent to over RMB 250 million of lost revenue, a sensitivity that compounds the headline 6-9 fen/W module premium [S2].
Selection Criteria Matrix: TOPCon vs BC vs HJT on Five Decision Gates
Stability: TOPCon 25-year cumulative degradation stays inside roughly 12%; BC 455 W units already hit 3.67% at 566 days in the Xi'an data set; HJT units crossed 3% on both retests [S2]. Module cost: TOPCon undercuts BC and HJT by 6-9 fen/W, with 0.07 yuan/W of additional headroom when bifacial gain is monetised [S2]. Scenario coverage: TOPCon commercial shipments already exceed 100 GW of cumulative volume across desert, high-altitude cold, coastal high-humidity, and rooftop sunroom deployments; BC and HJT have narrower field histories [S2]. Bankability: TOPCon's empirical first-year band of 0.52%-1.48% beats the commonly applied 2.0% first-year threshold, with five of six supplementary units also clearing the "≤ 0.6%/year subsequent" condition [S2]. Patent risk: TOPCon lines located in jurisdictions with issued '074 counterparts (US, EU, AU, CA, CN, JP, KR, etc.) face direct infringement exposure, while cells made in jurisdictions with pending-only coverage carry a different exposure profile [S1].
Who the Two Trends Are For — and Who They Are Not
Plant owners and EPCs underwriting 25-year LCOE bids with a hard ≤ 2.0% first-year degradation covenant benefit directly from the Xi'an TOPCon data set, because the empirical band leaves headroom against the threshold and against the typical 0.6%/year post-first-year test [S2]. Cell manufacturers shipping primarily into U.S., EU, Australian, Korean, or Japanese markets, or those OEMs whose module brands compete in those markets, must treat the '074 portfolio as a live licensing gate, not a theoretical risk, because of the issued counterpart geography and the 2030-and-beyond validity horizon [S1].
Conversely, HJT-only lines with documented first-year degradation above 3% in the Xi'an retests, and BC-only lines whose 455 W class modules already cross 2% within 566 days, are not the right fit for procurement officers targeting the "first-year ≤ 2.0%, subsequent annual ≤ 0.6%" envelope without contractual degradation make-good language [S2]. Startup perovskite–silicon tandem programmes, despite the wider research literature on improved carrier management in metal halide PSCs, remain outside the procurement envelope for utility-scale 1 GW LCOE bids in 2026, since the empirical evidence base for 25-year field degradation is not yet comparable to TOPCon's 100 GW-plus cumulative commercial footprint [S2][S3].
Limits, Failure Modes, and Sourcing Trackers
Two material caveats apply. First, the Xi'an test is one climate envelope (continental, with 41.8 °C/-20 °C extremes and 500-750 mm rainfall); extrapolating the TOPCon 0.52%-1.48% first-year band to coastal high-humidity, high-UV, or high-soiling sites requires parallel empirical coverage or aggressive derating [S2]. Second, the '074 suit, as of the 2025-02-26 public record, names only JinkoSolar and its related entities; First Solar's July 2024 statement indicated investigations were broader, so additional defendants remain a trackable signal even though the specific names are not in the public docket [S1].
Operators sizing 1 GW blocks should treat two signals as the next-90-day watchlist: (1) any further '074-family infringement filings in the District of Delaware or parallel actions in the EU, Korea, or Australia, all jurisdictions where the portfolio has issued counterparts; (2) follow-on Xi'an-style third-party empirical releases covering coastal humidity and high-UV sites, since the existing 0.52%-1.48% first-year band was generated in a single inland climate [S1][S2]. For cell sourcing, see the broader 2026 solar cell supplier map, and pair the TOPCon decision with the upstream solar glass supply picture and the solar glass supplier list so the module capex calculation is not blindsided by a separate feedstock gate. Plant-floor instrumentation choices around string monitoring, dataserver acquisition, and signal conditioning, increasingly relevant as TOPCon lines push higher currents, can be framed against the data logger selection gates and the signal conditioner buying guide.
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