Silicon Heterojunction Solar Cell Patent Landscape 2026
Silicon Heterojunction Solar Cell Patent Landscape in 2026
The silicon heterojunction solar cell field spans 563 patent families and is in a mature phase, with annual volume having eased from its 2021 peak while the multi-year window remains up. Tongwei Solar’s multiple subsidiaries collectively dominate, with China accounting for the largest share of filing activity, yet European and U.S. research institutions hold strong positions among the top-ranked applicants.
Tongwei Solar and REC Solar lead a moderately concentrated field
The top-ranked applicants are Tongwei Solar Energy (Chengdu), REC Solar, and the French Commissariat à l’Énergie Atomique (CEA), each contributing 47 patent records among the top 100 filers. The top five filers together account for 27% of the combined output of the hundred largest filers, indicating moderate rather than extreme concentration.
A clear tier gap exists between the top three applicants and the next tier: 3SUN and Trina Solar each contribute 31 and 27 patent records respectively, followed by a broader group of mid-tier filers in the teens and single digits. The field is competitive but not yet locked down by a single dominant player.
| # | Applicant | Patent records | Share |
|---|---|---|---|
| 1 | Tongwei Solar Energy (Chengdu) Co Ltd | 47 | |
| 2 | REC Solar Pte Ltd | 47 | |
| 3 | CEA (Commissariat à l’Énergie Atomique et aux Énergies Alternatives) | 47 | |
| 4 | 3SUN SRL | 31 | |
| 5 | Trina Solar Co Ltd | 27 | |
| 6 | Jiangxi Electric Investment New Energy Technology Co Ltd | 27 | |
| 7 | Tongwei Solar (Jintang) Co Ltd | 24 | |
| 8 | CSEM Centre Suisse d’Electronique et de Microtechnique SA | 21 | |
| 9 | LONGi Green Energy Technology Co Ltd | 19 | |
| 10 | JIANGSU WANJI DRIVE SCI & TECH CO LTD | 18 |
| # | Applicant | Patent records | Share |
|---|---|---|---|
| 11 | ENN Solar Energy Co Ltd | 17 | |
| 12 | École Polytechnique Fédérale de Lausanne (EPFL) | 15 | |
| 13 | Suzhou Aikang Low Carbon Technology Institute | 15 | |
| 14 | Tongwei Solar (Anhui) Co Ltd | 13 | |
| 15 | Darfon Materials Corporation | 13 | |
| 16 | Stanford University | 12 | |
| 17 | Tongwei Solar (Hefei) Co Ltd | 11 | |
| 18 | Energy Research Centre of the Netherlands (ECN) | 11 | |
| 19 | Tongwei Solar Energy (Meishan) Co Ltd | 11 | |
| 20 | Electric Investment New Energy Technology (Longgang) Co Ltd | 11 |
Tongwei Solar’s presence across at least five separately listed subsidiaries suggests a deliberate portfolio-fragmentation strategy; aggregating these entities would place the Tongwei group well ahead of all other individual applicants. This has implications for freedom-to-operate analyses, as Tongwei collectively controls a disproportionate share of recent filings in core device and process subclasses.
Patent records filed in approximately the last 18–24 months are subject to publication lag and are under-counted in this corpus; conclusions about very recent applicant momentum should be treated as provisional. Longer-window growth, applicant concentration, and technology-route coverage are therefore more reliable signals than the latest-year bar alone.
Activity peaked in 2021 and the technology mix is anchored in semiconductor device classification
The filing trend and IPC composition together reveal a maturing field with a dominant core technology class and several adjacent branches that remain comparatively sparse.
Annual filing trend
Annual filings climbed sharply from 34 records in 2017 to a peak of 112 in 2021, then eased to 104 in 2022 and continued declining through 2023 and 2024. The 2025 and 2026 figures reflect publication lag and should not be read as a structural decline. The multi-year growth window remains positive at 12%, consistent with a field that has plateaued near its peak rather than contracted.
↗ Hover for values · click a bar to ask EurekaTechnology composition
H01L (Semiconductor devices) accounts for the overwhelming majority of classified records, confirming that core device architecture—junction formation, passivation, and contact design—dominates R&D attention. Coating and surface deposition (C23C) and cables/conductors (H01B) are secondary branches with meaningful but far smaller representation. Organic semiconductor (H10K) and photovoltaic device (H10F) classes are present at low levels, signalling selective exploration of tandem and next-generation architectures.
↗ Hover for values · click a bar to ask EurekaHighly cited patent families surfaced by the query
Citation-heavy patent families returned by the query. Use this section as citation context, not as a curated list of the most topic-specific patents.
High-efficiency silicon heterojunction solar cell …
The present disclosure discloses a high-efficiency silicon heterojunction (HJT) solar cell and a manufacturing method thereof, and belongs to the technical field of solar cells. In the solar cell of the present disclosure, an N-type crystal silicon wafer is successively provided with a thin SiO<sub>2 </sub>layer, a hydrogenated amorphous carbon silicon… (excerpt from the patent abstract)
| # | Patent | Citations |
|---|---|---|
| 1 | Method of manufacturing an amorphous/crystalline s… | 96 |
| 2 | Device comprising electrical contacts and its prod… | 59 |
| 3 | Process for producing a solar cell by means of epi… | 57 |
| 4 | Indium oxide/n-silicon heterojunction solar cells | 47 |
| 5 | 双面受光的晶体硅/薄膜硅异质结太阳电池及制作方法 | 43 |
| 6 | Method for fabricating solar cells having integrat… | 36 |
| 7 | Solar cells having integral collector grids | 33 |
| 8 | 一种具有电镀电极的硅异质结太阳能电池及其制作方法 | 32 |
Ranked by total forward citations. Citation counts favour older and broadly cited patent families, and broad or adjacent patents may appear when they match the search scope. Treat this section as citation context, not as a curated list of the most topic-specific patents. Some patent titles may be shown in their original, non-English language where an accurate translation could not be guaranteed.
What the structure means for R&D strategy
Four structural observations—maturity stage, concentration pattern, collaboration network, and geographic spread—define the strategic context for any new entrant or incumbent seeking to reposition.
Field has plateaued near its 2021 peak
Annual filing volume peaked in 2021 and has eased since, placing the field at the Maturity stage. Multi-year growth remains positive at 12%, so the field has not entered decline, but the window for staking out foundational positions in core device architecture is largely closed. R&D investment is best directed at differentiated subclasses or next-generation integration rather than re-prosecuting well-covered ground.
Maturity stageModerate concentration with a multi-subsidiary leader
The top five filers hold 27% of the combined output of the hundred largest filers—a moderate concentration level that leaves room for challengers. However, Tongwei Solar’s fragmented subsidiary structure means its true aggregate share is higher than any single ranked entity suggests. New entrants should map the full Tongwei group portfolio before defining white-space entry points. European institutions (CEA, CSEM, EPFL) and manufacturer REC Solar provide alternative citation anchors outside the Chinese manufacturing cluster.
Competitive structureCEA–3SUN and Tongwei intra-group co-filings dominate the network
The most active co-filing pair is CEA (Commissariat à l’Énergie Atomique) and 3SUN, with 14 jointly filed records, reflecting a deep manufacturer–research-institute alliance. Tongwei Solar’s four subsidiaries co-file extensively with each other (11 records per pair), suggesting coordinated portfolio management rather than independent R&D. A secondary axis links the State Power Investment Corporation research institute with Jiangxi Electric Investment New Energy, with 7 co-filed records. CEA also co-files with ENN Solar Energy (5 records), indicating cross-border industry–academia collaboration.
EcosystemChina leads; Europe and the U.S. are meaningful secondary jurisdictions
China is the primary filing jurisdiction, followed by Europe (EPO), the United States, and WIPO PCT filings. Australia and India appear as growth markets with notable coverage. Taiwan, Germany, Singapore, Japan, and South Korea round out the secondary tier. The multi-jurisdictional spread, particularly via PCT, indicates that leading applicants are actively seeking international protection, raising the barrier for regional market entry without a freedom-to-operate clearance.
Jurisdiction spreadGo beyond the landscape: Eureka’s TRIZ Solution agent breaks down an R&D problem and returns patented concept solutions, each with a technical approach and cited patent & literature evidence.
| Applicant | Collaborator | Co-filings |
|---|---|---|
| CEA (Commissariat à l’Énergie Atomique et aux Énergies Alternatives) | 3SUN SRL | 14 |
| Tongwei Solar Energy (Chengdu) Co Ltd | Tongwei Solar (Jintang) Co Ltd | 11 |
| Tongwei Solar Energy (Chengdu) Co Ltd | Tongwei Solar Energy (Meishan) Co Ltd | 11 |
| Tongwei Solar Energy (Chengdu) Co Ltd | Tongwei Solar (Anhui) Co Ltd | 11 |
| Tongwei Solar Energy (Chengdu) Co Ltd | Tongwei Solar (Hefei) Co Ltd | 11 |
| Tongwei Solar (Jintang) Co Ltd | Tongwei Solar Energy (Meishan) Co Ltd | 11 |
| Tongwei Solar (Jintang) Co Ltd | Tongwei Solar (Anhui) Co Ltd | 11 |
| Tongwei Solar (Jintang) Co Ltd | Tongwei Solar (Hefei) Co Ltd | 11 |
| State Power Investment Corporation Research Institute | Jiangxi Electric Investment New Energy Technology Co Ltd | 7 |
| CEA (Commissariat à l’Énergie Atomique et aux Énergies Alternatives) | ENN Solar Energy Co Ltd | 5 |
Co-filing pairs, ranked by the number of jointly-filed patent families.
Tongwei Solar and REC Solar lead; Trina Solar is an accelerating challenger
The top two ranked applicants are tied on patent records count, but differ sharply in trajectory and technology emphasis. A fast-rising challenger has entered the top tier recently.
Tongwei Solar Energy (Chengdu)
Tongwei Solar Energy (Chengdu) holds 47 patent records and is the single highest-ranked individual entity in the corpus. Its technology focus is concentrated almost entirely on H01L 31 (semiconductor device subclass covering photovoltaic cells), with a secondary position in coating and surface deposition (C23C 14) and crystal growth (C30B), indicating attention to both device architecture and upstream material processes. Momentum is positive at +36% recent versus prior period, placing it among the more active current filers in the top tier.
patent records: 47Trina Solar
Trina Solar contributes 27 patent records and is classified as a new entrant in momentum terms—all of its recent filings are concentrated in the current measurement window, signalling a deliberate late-stage push into silicon heterojunction IP. Its technology emphasis spans H01L 31 as the dominant subclass, with secondary activity in photovoltaic device classifications H10F 77 and H10F 10, suggesting interest in next-generation cell architectures beyond the classical HJT structure. This trajectory warrants monitoring as an emerging competitive threat to established leaders.
patent records: 27| Applicant | Recent (3 yrs) | Trend |
|---|---|---|
| CEA (Commissariat à l’Énergie Atomique et aux Énergies Alternatives) | 3 | ▼ -83% |
| REC Solar Pte Ltd | 24 | ▬ +4% |
| Trina Solar Co Ltd | 27 | ▲ new entrant |
| Tongwei Solar Energy (Chengdu) Co Ltd | 15 | ▲ +36% |
| 3SUN SRL | 3 | ▼ -86% |
| Tongwei Solar (Jintang) Co Ltd | 7 | ▼ -59% |
| State Power Investment Corporation Research Institute | 1 | ▲ new entrant |
| Zhongwei New Energy (Chengdu) Co Ltd | 10 | ▼ -17% |
Under-served adjacent branches worth watching
Several IPC classes appear at low share relative to the dominant H01L core, representing areas where patent density is sparse. Some of these carry plausible technical relevance to silicon heterojunction cells and may represent viable entry points for differentiated filings.
H10F · Photovoltaic & light-sensitive devices
H10F covers photovoltaic and light-sensitive device architectures under the reclassified IPC scheme, and holds only 14 records in this corpus—a 1% share of classified records. As the IPC reclassification of solar cell art migrates coverage from H01L 31 into H10F, early prosecution in this subclass could establish prior-art anchors for tandem cell and next-generation HJT architectures before competitors recognize the reclassification shift. The entry path is straightforward: claims directed at device-level HJT innovations drafted with H10F classification in mind, particularly for perovskite-silicon tandem structures.
Search this in Eureka →C23C · Coating & surface deposition
Coating and surface deposition (C23C) accounts for 60 records—a 6% share—making it the largest adjacent branch after the dominant H01L class, yet still sparse relative to the complexity of thin-film deposition steps central to HJT manufacturing (PECVD intrinsic and doped amorphous silicon layers, ITO sputtering). The sparse coverage suggests that process-level innovations in deposition chemistry, precursor selection, and layer uniformity are underrepresented. Applicants with deposition-equipment or materials capabilities could build differentiated positions here without directly contesting the dense H01L device-architecture space.
Search this in Eureka →How leaders differ by technology route
Strength of each leader across the main technology routes.
| Player | H01L 31 · Semiconductor devices | H01B 1 · Cables, conductors & insulators | H01L 21 · Semiconductor devices | C23C 16 · Coating & surface deposition | C23C 14 · Coating & surface deposition |
|---|---|---|---|---|---|
| CEA (Commissariat à l’Énergie Atomique et aux Énergies Alternatives) | Strong · 45 | Absent | Emerging · 4 | Absent | Absent |
| REC Solar Pte Ltd | Strong · 47 | Absent | Emerging · 1 | Absent | Absent |
| Zhongwei New Energy (Chengdu) Co Ltd | Strong · 22 | Absent | Emerging · 2 | Absent | Moderate · 5 |
| Jiangsu Wanji Drive Science & Technology Co Ltd | Absent | Absent | Strong · 9 | Strong · 10 | Strong · 10 |
| Trina Solar Co Ltd | Strong · 26 | Absent | Absent | Absent | Absent |
| Tongwei Solar Energy (Chengdu) Co Ltd | Strong · 26 | Absent | Absent | Absent | Absent |
| State Power Investment Corporation Research Institute | Strong · 22 | Absent | Emerging · 2 | Absent | Emerging · 1 |
Frequently asked questions
The corpus covers 563 patent families. This figure represents the deduplicated family count in scope; individual jurisdiction filings derived from those families produce a higher count of patent records across the classified corpus.
Tongwei Solar Energy (Chengdu), REC Solar, and CEA (Commissariat à l’Énergie Atomique) are the top three ranked applicants, each with 47 patent records among the top 100 filers. Tongwei Solar’s additional subsidiaries—Tongwei Solar (Jintang), Tongwei Solar (Anhui), Tongwei Solar (Hefei), and Tongwei Solar (Meishan)—collectively amplify the group’s aggregate position.
The field is assessed at the Maturity stage. Annual filings peaked in 2021 at 112 records and have eased since, though the multi-year growth window remains positive at 12%. The field has plateaued near its peak rather than entered decline.
China is the primary jurisdiction, followed by Europe (EPO), the United States, and WIPO PCT. Australia and India are notable secondary markets. Filings have also been made in Taiwan, Germany, Singapore, Japan, South Korea, France, and a range of other jurisdictions, indicating broad international protection strategies by leading applicants.
The most-cited work in the corpus is a patent titled ‘Method of manufacturing an amorphous/crystalline silicon heterojunction solar cell,’ with 96 citations, followed by ‘Device comprising electrical contacts and its production’ (59 citations) and ‘Process for producing a solar cell by means of epitaxial growth’ (57 citations). An early paper on indium oxide/n-silicon heterojunction solar cells (47 citations) is also among the most-referenced works.
The most technically relevant adjacent branches with sparse coverage are H10F (Photovoltaic and light-sensitive devices, 14 records) and C23C (Coating and surface deposition, 60 records). H10F is particularly notable because IPC reclassification is migrating solar cell art into this class, potentially creating early-mover advantage. C23C is sparse relative to the centrality of thin-film deposition in HJT manufacturing and may offer differentiated positioning for process or materials innovators.
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