TOPCon vs HJT in 2026: where the cost curves actually cross
TOPCon will dominate module shipments through 2027, but HJT's per-watt manufacturing cost gap has closed faster than analysts forecast in 2025. Here is the data — and why developers in India should keep a 12-month watching brief on HJT before committing to TOPCon-only pipelines.
In 50 words: TOPCon holds 78% of mainstream module shipments entering Q2 2026, but HJT's per-watt manufacturing cost has narrowed from a 12% premium in 2024 to 4% in March 2026. For Indian developers signing 25-year offtakes today, an HJT watching brief is now mandatory due diligence.
The state of play
TOPCon (Tunnel Oxide Passivated Contact) became the workhorse of crystalline silicon in 2024–2025. By March 2026, it accounts for roughly 78% of new cell production capacity worldwide, with average cell efficiency in mass production at 25.7% per ITRPV's 2026 roadmap edition.
HJT (Heterojunction) sits at about 11% of shipments — but with a meaningfully higher efficiency floor, 25.9% average and 26.4% on best lines. The historical knock against HJT was capex per GW and indium dependence on the transparent conductive oxide layer.
Why the gap is closing faster than 2025 forecasts
Three drivers:
- Silver paste cuts. Industry-wide silver-to-copper transition on HJT busbars dropped grams-per-watt of silver by 38% between Q1 2025 and Q1 2026.
- Indium-free TCO trials. Two Tier 1 HJT producers shipped commercial volumes of zinc-oxide-based TCO in Q1 2026, removing the indium supply risk that had inflated long-run cost models.
- Equipment depreciation curve. New HJT lines installed in 2024–2025 are now off the steepest part of their commissioning curve, with yields in mass production crossing 97%.
What this means for Indian developers
Tenders being bid in mid-2026 with module delivery in 2027–2028 should treat HJT as a real option, not a future technology. Practical recommendations:
- Lock TOPCon supply for 2026 commissioning. The supply chain is mature, ALMM List-III certified options are plentiful, and tariffs are at floor levels.
- For 2027+ commissioning, structure module supply contracts with technology-substitution clauses. The cost-of-energy difference at 26.4% cell efficiency over 25 years is non-trivial on a per-MWh basis.
- Track at least two HJT manufacturers with operating Indian or India-bound capacity for ALMM listing trajectory.
What to watch next
The next inflection point sits at the back-contact cell. Tongwei's IBC line and Aiko's ABC platform both crossed 26.5% mass-production efficiency in Q1 2026. If back-contact moves from under 2% of shipments today to over 10% by late 2027, the HJT-vs-TOPCon framing becomes a three-way race.
Researched and drafted with AI assistance; reviewed and edited by the named author within 24 hours of draft. See our editorial standards and AI disclosure.