Both TOPCon and HJT are N-Type technologies. Both beat Mono PERC comfortably. Both are marketed as the future of solar. And if you are specifying modules for an Indian project in 2026, only one of them is realistically available at scale.
This is a straight comparison of the two leading next-generation cell technologies: how they differ physically, where each genuinely outperforms, what they cost, and what the Indian supply situation actually looks like now that heterojunction cell capacity has appeared on the approved list. If you want the broader landscape first, start with our guide to the types of solar panels.
What is an HJT solar panel?
HJT stands for heterojunction technology. An HJT cell sandwiches a crystalline silicon wafer between ultra-thin layers of amorphous silicon, creating a junction between two different types of silicon. That is the heterojunction: two dissimilar materials meeting.
Those amorphous layers passivate the wafer surface exceptionally well, which is what gives HJT its two signature strengths: very high efficiency and an unusually low temperature coefficient. HJT cells are inherently bifacial with high bifaciality factors, and the process runs at low temperature, typically under 200 degrees Celsius, which is gentler on the wafer and allows thinner silicon.
The trade-off is manufacturing complexity. HJT lines need different equipment from conventional cell lines, use more silver paste, and require low-temperature processing throughout. You cannot upgrade a PERC line to HJT the way you can to TOPCon. That single fact explains most of what follows.
What is a TOPCon solar panel?
TOPCon stands for tunnel oxide passivated contact. A TOPCon cell adds an ultra-thin tunnel oxide layer and a doped polysilicon layer on the rear of an N-Type wafer. The oxide is thin enough for charge carriers to tunnel through while blocking recombination, which lifts efficiency well above Mono PERC.
Crucially, TOPCon lines can be built by upgrading existing PERC equipment rather than replacing it. Manufacturers could add TOPCon capacity incrementally, which is precisely why it scaled so fast globally and in India. Our N-Type vs P-Type guide covers the underlying cell physics in more detail.
TOPCon vs HJT: the head-to-head
|
TOPCon |
HJT |
|
|
Typical module efficiency |
22 to 24% |
22.5 to 24.5% |
|
Temperature coefficient |
Around -0.29 to -0.30%/°C |
Around -0.24 to -0.26%/°C |
|
Bifaciality factor |
Roughly 70 to 85% |
Roughly 85 to 95% |
|
First-year degradation |
Low, no LID |
Low, no LID |
|
Manufacturing route |
Upgrade from PERC lines |
Entirely new line required |
|
Silver consumption |
Moderate |
Higher |
|
Indian ALMM cell capacity |
Dominant share |
Newly listed, small share |
|
Indicative price per watt |
₹20 to ₹26 |
₹30 to ₹38 |
Read that table carefully and a pattern emerges. On pure physics, HJT edges ahead on almost every performance metric. On everything to do with manufacturing and supply, TOPCon wins decisively. For most Indian projects the second column matters more than the first, but not for all of them.
Where HJT genuinely wins
It would be dishonest to present HJT as merely an expensive TOPCon. It is better technology in specific, measurable ways.
Heat tolerance
The lower temperature coefficient means HJT loses less output as cell temperature rises. On a rooftop in Rajasthan or Gujarat in May, where module temperatures pass 65 degrees Celsius, that difference compounds across the hottest hours of the highest-generation months.
Bifacial gain
Higher bifaciality means more rear-side generation from reflected light. On elevated ground-mount arrays over light-coloured surfaces, this is real additional yield.
Efficiency headroom
HJT holds a higher theoretical and record-cell ceiling, tracked in NREL's Best Research-Cell Efficiency Chart. If maximum watts per square metre is your binding constraint, HJT leads.
Long-term degradation
HJT typically posts very low annual degradation rates, which matters over a 30-year asset life.
If you are building a large ground-mount project in a hot state with unconstrained capital and no domestic content requirement, HJT deserves serious evaluation.
Where TOPCon wins in India
For the majority of Indian projects, four practical factors decide it.
Availability under ALMM
Since 1 June 2026, government-backed, net-metered and open-access projects must use modules built with domestically produced cells approved under ALMM List-II. India's listed cell capacity passed 30 GW in 2026, and the overwhelming majority of it is TOPCon. Heterojunction capacity has only just entered the list. If your project needs ALMM compliance, TOPCon is what exists.
Price per watt
TOPCon modules run roughly ₹20 to ₹26 per watt in Indian commercial lot sizes against ₹30 to ₹38 for HJT. On a 1 MW project that gap is substantial, and it buys more installed capacity than the efficiency difference recovers.
Supply depth
Multiple Indian manufacturers run TOPCon lines at scale, so you have negotiating leverage, second sources and replacement availability. HJT supply in India is concentrated in very few hands. Our guide to the top solar panel manufacturers in India shows how the capacity is distributed.
Weak-light performance
Both technologies handle low irradiance well. For Indian monsoon conditions, TOPCon's weak-illumination response is already a substantial improvement over the PERC modules most buyers are replacing, and the incremental HJT gain is smaller than the price gap.
This is why TOPCon has become the latest solar panel technology in India in practical terms, not just in marketing copy. Atal Solar's G12R 132 Series reaches up to 23.51% module efficiency, which sits inside the range where the HJT premium becomes hard to justify for rooftop and C&I work.
HJT solar panel price and availability in India
HJT modules in India indicatively run ₹30 to ₹38 per watt against ₹20 to ₹26 for TOPCon, a premium of roughly 40 to 50%. Higher silver consumption and dedicated production lines drive most of that gap, and the premium narrows as volumes rise but has not closed.
Availability is the sharper constraint. Heterojunction cell capacity appeared on India's ALMM List-II during 2026, with Reliance Industries adding HJT capacity in the revision published on 30 April 2026. That is genuinely significant: it is the first meaningful domestic HJT cell capacity approved for use in government-linked projects. But it remains a small fraction of the roughly 30 GW of listed cell capacity, nearly all of which is TOPCon.
The practical consequence for a 2026 procurement decision: if your project requires ALMM-compliant modules, TOPCon offers genuine choice among suppliers while HJT does not yet. Check the current position on the MNRE site before finalising a specification, because this is moving. For current module pricing, see our TOPCon solar panel price guide.
Which should you actually specify?
There is no universal answer, but the decision is fairly clean:
|
Your situation |
Specify |
|
Residential rooftop under PM Surya Ghar |
TOPCon. ALMM compliance and price decide it. |
|
C&I rooftop, cost-sensitive |
TOPCon. Better cost per unit generated. |
|
Government or net-metered project |
TOPCon. Domestic cell availability decides it. |
|
Ground-mount in a very hot state, capital available |
Evaluate HJT seriously against TOPCon on modelled yield. |
|
Severely space-constrained, watts per m² binding |
Evaluate HJT, but check ALMM eligibility first. |
|
Export project, no domestic content requirement |
Either. Decide on modelled LCOE. |
Whichever way you lean, model it rather than assuming. Ask both suppliers for full datasheets with temperature coefficients, bifaciality factors and degradation curves, then run your own yield model against your site conditions. A manufacturer that will not give you those numbers has told you something useful.
You can download complete N-Type TOPCon datasheets from our Download Center, or request a quote for modules manufactured on a fully automated line with AI and AOI robotic inspection in Rajkot, Gujarat. WhatsApp us at +91 90990 88489.
Frequently asked questions
What is the difference between TOPCon and HJT solar panels?
TOPCon adds a tunnel oxide and polysilicon layer to the rear of an N-Type wafer. HJT sandwiches the wafer between amorphous silicon layers. HJT has a slightly higher efficiency ceiling and better temperature coefficient; TOPCon is cheaper and far more widely available in India.
Is HJT better than TOPCon?
On raw performance metrics, marginally yes. On availability, price and supply depth in India, no. For most Indian projects in 2026, TOPCon delivers better cost per unit of electricity generated because the HJT premium of 40 to 50% exceeds its performance advantage.
What is the HJT solar panel price in India?
Indicatively ₹30 to ₹38 per watt in 2026, against ₹20 to ₹26 for N-Type TOPCon. Higher silver consumption and dedicated manufacturing lines drive the premium. Figures as of August 2026; verify current rates before procurement.
Are HJT solar panels available in India?
Availability is limited but improving. Heterojunction cell capacity entered India's ALMM List-II during 2026, but it remains a small share of roughly 30 GW of listed cell capacity, nearly all of which is TOPCon.
Which is the latest solar panel technology in India?
N-Type TOPCon is the current mainstream technology across Indian manufacturing, having largely displaced Mono PERC. HJT and back-contact designs sit at the leading edge but hold small capacity shares domestically.
Should I wait for HJT prices to fall before installing solar?
Generally no. Delaying installation costs you generation and possibly subsidy eligibility, and the price gap has narrowed slowly rather than collapsed. A TOPCon system installed now will typically outperform an HJT system installed several years later on lifetime economics.
