HJT vs. TOPCon: The Battle for the Next Generation of Solar Efficiency
Release time: 2026-01-27
Table of Contents
In this blog, we’ll explore how HJT and TOPCon panels work, their key differences, and which might be the better choice for your solar project. Whether you’re a homeowner, installer, or solar business owner, understanding these technologies can help you make more informed decisions.
The N-Type Revolution: Why P-Type PERC is Fading
Before diving into the specific rivalry between HJT and TOPCon, it is crucial to understand the context. For the last decade, the solar industry was dominated by P-type PERC (Passivated Emitter and Rear Cell) technology. It was reliable and cost-effective. However, PERC has hit its theoretical efficiency limit (around 24%).
To break through this ceiling, the industry has shifted to N-type cells. N-type silicon is doped with phosphorus rather than boron, making it virtually immune to Light Induced Degradation (LID) and capable of much higher efficiencies.
The two frontrunners in this N-type race are TOPCon (Tunnel Oxide Passivated Contact) and HJT (Heterojunction). Both promise more power per square meter, but they achieve it in very different ways.
What is TOPCon Solar Technology?
TOPCon stands for Tunnel Oxide Passivated Contact. It is widely considered the pragmatic successor to PERC technology because it allows manufacturers to upgrade existing production lines rather than building new ones from scratch.
How It Works
TOPCon adds a microscopic layer of ultra-thin tunneling oxide and a polysilicon layer to the rear of the cell. This “passivation” layer allows current to flow freely while preventing the recombination of electrons (which causes energy loss).
- Key Advantage: It minimizes surface recombination, boosting conversion efficiency significantly over PERC.
- Manufacturing: Because it builds upon the PERC structure, it offers a lower Capital Expenditure (CapEx) for manufacturers, leading to competitive pricing for end-users.
What is HJT Solar Technology?
HJT stands for Heterojunction with Intrinsic Thin-layer. It is often viewed as the “premium” technology with the highest theoretical potential, blending the best attributes of crystalline silicon and thin-film technology.
How It Works
HJT places an N-type crystalline silicon wafer between two layers of amorphous thin-film silicon. This “sandwich” structure is incredibly effective at capturing energy. The amorphous silicon layers act as excellent passivation, significantly reducing electron loss.
- Key Advantage: HJT boasts a symmetrical structure, which naturally leads to extremely high bifaciality (the ability to generate power from the backside of the panel).
- Manufacturing: HJT requires a completely different manufacturing process at lower temperatures. While this reduces energy consumption during production, it requires expensive new equipment, keeping the market price of HJT panels slightly higher.
Head-to-Head Comparison: HJT vs. TOPCon
To decide which is better for your project, we must look at the technical metrics that impact ROI (Return on Investment) and LCOE (Levelized Cost of Energy).
1. Efficiency Rates
Both technologies surpass the 25% cell efficiency mark, leaving traditional PERC (22-23%) behind.
- TOPCon: Currently achieves mass production efficiencies of 25% – 26%.
- HJT: Slightly edges ahead with mass production efficiencies often exceeding 26%, with lab records pushing toward 27%+.
- Winner: HJT (Marginal Lead)
2. Temperature Coefficient
This is a critical, often overlooked metric. It measures how much power a panel loses for every degree Celsius significantly above 25°C (77°F).
- TOPCon: typically around -0.30%/°C.
- HJT: typically around -0.26%/°C.
- Why it matters: In hot climates (e.g., California, Australia, Middle East), HJT panels will retain more of their rated power output on a hot afternoon than TOPCon.
- Winner: HJT
3. Bifaciality (Rear-Side Generation)
For ground-mounted utility projects or commercial rooftops with reflective surfaces (white TPO roofs), bifaciality is key.
- TOPCon: Bifaciality factor of 80-85%.
- HJT: Bifaciality factor of 85-95%.
- Winner: HJT
4. Degradation and Reliability
N-type cells naturally suffer less degradation than P-type. However, there are nuances.
- TOPCon: Sensitive to moisture ingress. Solar panels manufacturers must use high-quality encapsulants (POE) to prevent corrosion. First-year degradation is ~1%.
- HJT: Extremely stable but the TCO (Transparent Conductive Oxide) layer can be sensitive to UV and moisture if not sealed correctly. First-year degradation is often <1%.
- Winner: Tie (Dependent on Manufacturing Quality)
5. Cost and Availability
This is where TOPCon strikes back.
- TOPCon: Because manufacturers could retrofit existing factories, the supply chain is robust, and costs are only marginally higher than PERC.
- HJT: Requires varying production lines and expensive silver paste (though busbarless technology is reducing this). It commands a price premium.
- Winner: TOPCon
Technical Specifications Snapshot
| Feature | TOPCon (Tunnel Oxide Passivated Contact) | HJT (Heterojunction) |
| Cell Structure | N-type Crystalline + Tunnel Oxide | Crystalline + Amorphous Thin Film |
| Lab Efficiency Limit | ~28.7% | ~29.2% |
| Mass Production Efficiency | 25.0% – 26.0% | 25.5% – 26.5% |
| Temperature Coefficient | -0.29% to -0.32% / °C | -0.24% to -0.26% / °C |
| Bifacial Factor | 80% ± 5% | 90% ± 5% |
| Manufacturing Cost | Medium (Low CapEx) | High (High CapEx) |
| Best Application | Residential & Utility Scale (Cost-Sensitive) | Premium Residential & High-Heat Areas |
The Verdict: Which Should You Choose?
The “better” panel depends entirely on the specific constraints of your installation.
Choose TOPCon If:
- You want the best value for money. TOPCon solar panel offers a significant performance jump over older technologies without the steep price tag of HJT.
- You are limited by budget. For large-scale utility projects where a $0.01/watt difference adds up to millions, TOPCon provides the lowest LCOE.
- Space is not the #1 constraint. While efficient, if you have ample roof space, the slight efficiency gain of HJT might not justify the extra cost.
Choose HJT If:
- You live in a hot climate. The superior temperature coefficient means HJT will outperform TOPCon significantly during summer heatwaves.
- You have limited roof space. If you need to squeeze the maximum possible wattage out of a small roof, HJT’s higher efficiency density is worth the premium.
- You are installing a ground mount. The high bifaciality (up to 95%) allows HJT to harvest massive amounts of energy from the rear side if installed over light-colored ground or concrete.
Future Outlook: The Market Trends
As of 2026, TOPCon currently holds the larger market share due to the ease of manufacturing scalability. Most Tier 1 solar panel manufacturers (like Jinko, Trina, and Amosolar) have bet heavily on TOPCon.
However, HJT is gaining ground as manufacturing costs drop. Innovators (like REC, Huasun, and Risen) are optimizing the silver consumption in HJT cells, slowly narrowing the price gap. We are also seeing the emergence of HBC (Heterojunction Back Contact), which attempts to combine the aesthetics of back-contact cells with the performance of HJT.
FAQ: HJT and TOPCon Common Questions
Q: Do HJT panels last longer than TOPCon?
A: Both technologies typically offer 30-year power warranties, which is superior to the industry standard 25 years. HJT generally has slightly lower annual degradation rates (-0.35% vs -0.4%), potentially resulting in 2-3% more retained power at year 30.
Q: Is HJT compatible with standard inverters?
A: Yes. While HJT panels often have higher voltages and lower currents than standard panels, they are compatible with most modern string inverters and microinverters. Always check the voltage window of your inverter before sizing strings.
Q: Why are HJT panels more expensive?
A: HJT cells require a more complex manufacturing process involving vacuum deposition and historically use more silver paste for conductivity. Additionally, the equipment cannot be retrofitted from old lines; it must be built new.
Need Help Sourcing N-Type Modules?
Navigating the shift from P-type to N-type technology can be complex. Whether you need the cost-efficiency of TOPCon or the premium performance of HJT, ensuring you select a Tier 1 manufacturer is vital for long-term warranty security.
[Contact Amosolar Today] to discuss your project requirements and get a quote on the latest N-type solar solutions.
