Solar Panel Cell Technology Explained: PERC, TOPCon, HJT and What They Mean for You

TOPCon, HJT, N-Type, i-TOPCon — solar panel listings throw a lot of terminology at you, and the store filters rarely bother to explain any of it. Behind all of it, though, are just a handful of core cell technologies rooted in specific physics and materials science. This guide covers every technology you'll encounter when buying solar panels in 2026 — what it is, how it performs, what it costs, and how to choose.

The foundation: P-Type vs N-Type silicon

Before diving into specific technologies, there’s one concept that clarifies almost everything else: the type of silicon wafer at the core of the cell.

All standard solar cells are built on a crystalline silicon base, called a wafer. That wafer is “doped” — meaning trace amounts of another element are introduced to change its electrical properties. There are two options:

The practical difference matters enormously over the lifetime of a panel. P-type silicon is vulnerable to a phenomenon called Light-Induced Degradation (LID): when boron and oxygen atoms bond in the presence of light, they form defects that permanently reduce efficiency. This typically costs a P-type panel 1–3% of its rated output in the first few hours of sun exposure.

N-type solar panels has no boron, so it has no LID whatsoever. It also has a longer minority carrier lifetime — meaning the electrons generated by sunlight have more time to reach the circuit before recombining and being lost as heat. The result is higher inherent efficiency, lower degradation over time, and better performance in hot weather.

PERC — the technology that modernized solar

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For most of the 2010s, PERC was the answer to the question “what’s the best solar panel?” It remains relevant, but its era of dominance is over.

What PERC is. PERC stands for Passivated Emitter and Rear Cell. Standard silicon cells lose a significant amount of energy through their back surface: electrons generated by sunlight that aren’t immediately collected recombine at the rear of the wafer and are lost as heat. PERC solves this by adding a passivation layer to the back of the cell — a thin dielectric film that reflects unabsorbed photons back into the silicon for a second chance at conversion, while simultaneously reducing surface recombination.

The result was a meaningful efficiency jump over standard mono cells with minimal added manufacturing complexity. PERC solar panels from major manufacturers typically reach 20–22% module efficiency.

Performance profile:

Market status. PERC dominated global solar production from roughly 2017 to 2023. In 2024, TOPCon surpassed PERC as the leading technology for the first time — TOPCon manufacturing capacity reached approximately 66% of global installed capacity, while PERC’s share of shipped modules fell to around 35–40%. PERC is now on a managed decline, with major manufacturers actively phasing out PERC lines. It remains a cost-effective option for budget-sensitive installations where maximizing watt-per-dollar outweighs long-term yield.

Brand spotlight: Q.ANTUM by Hanwha Qcells

Hanwha Qcells didn’t just adopt PERC — they were the first company to commercialize it at scale, and their branded implementation is called Q.ANTUM. Beyond the standard PERC architecture, Q.ANTUM adds three proprietary protections: Anti-LeTID Technology (which mitigates Light and elevated Temperature Induced Degradation, a long-term P-type degradation mechanism), Anti-PID Technology (guards against Potential-Induced Degradation in humid environments), and Hot-Spot Protect (reduces the risk of localized overheating from partial shading).

In plain terms: Q.ANTUM = PERC + Qcells’ quality and yield-protection layer. It’s a mature, well-proven technology with a long track record in the field.

TOPCon — the new standard

TOPCon is now the mainstream solar cell technology globally, and understanding how it works explains why.

What TOPCon is. TOPCon stands for Tunnel Oxide Passivated Contact. The technology was developed at Germany’s Fraunhofer Institute for Solar Energy Systems in 2013 and entered mass production with Chinese manufacturers around 2019–2020. It builds on the N-type wafer and adds a critical innovation at the rear contact.

In conventional cells — including PERC — the metal contacts that collect electrons must physically touch the silicon. Every contact point is a site of recombination loss. TOPCon inserts an ultra-thin layer of silicon oxide (~1–2 nanometers, just a few atoms thick) between the silicon wafer and the polycrystalline silicon layer behind it. This oxide layer is thin enough that electrons can pass through it via quantum tunneling — a physics phenomenon where particles can cross a barrier too thin to block them classically. Critically, the same oxide layer suppresses the movement of minority carriers (the ones we don’t want to collect), dramatically reducing recombination and raising open-circuit voltage.

The net effect: higher efficiency from the same surface area, with better stability over time.

Performance profile:

• Module efficiency: 22–25.5%
• Annual degradation: ~0.4%/yr
• Temperature coefficient: ~-0.31%/°C
• LID: None (N-type substrate)
• Bifaciality: 80–90% (most TOPCon panels are bifacial)
• Wholesale price (2026): ~$0.28–0.35/W

Panels with TOPCon cells crossed 65% of global production capacity in 2024 — the first time any technology other than PERC had led since the early 2010s. In February 2026, JinkoSolar and the Chinese Academy of Sciences published results in Nature Energy reporting a certified 26.66% efficiency for an industrial-scale TOPCon cell on an M10 wafer — 83.8% of the theoretical efficiency limit for silicon.

Brand spotlight: Q.ANTUM NEO by Hanwha Qcells

Just as Q.ANTUM is Qcells’ implementation of PERC, Q.ANTUM NEO is their implementation of N-type TOPCon — and it represents a meaningful advance over standard TOPCon.

The key innovation is what Qcells calls the “NEO Power Transmitter” layer. In standard PERC, the passivation layer must be punctured at contact points, compromising the passivation quality at exactly the spots where it matters most. Q.ANTUM NEO integrates passivation and electrical contact functions in the same layer, achieving full-area passivation without sacrificing conductivity — the fundamental limitation of the original Q.ANTUM/PERC architecture.

Other leading TOPCon brands at A1 SolarStore: JinkoSolar (global production leader, 80+ GW of N-type capacity), Trina Solar, Canadian Solar (modules up to 690W output), JA Solar, LONGi.

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Meyer Burger 375W Solar Panel 120 Cell All-Black MB_B120AyB_375 Clearance

• Rated Power Output 375 W
• Voltage (VOC)44.4 V
• Number of cells120 Cell
• Cell TypeMonocrystalline

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JA Solar 380W Solar Panel 72 Cell JAM72S09-380/PR Clearance

• Rated Power Output 380 W
• Voltage (VOC)48.75 V
• Number of cells72 Cell
• Cell TypeMonocrystalline

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Jinko 410W Solar Panel 144 Cell JKM410M-72HL-V Clearance

• Rated Power Output 410 W
• Voltage (VOC)50.4 V
• Number of cells144 Cell
• Cell TypeMonocrystalline

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HJT — the premium choice

HJT is the most technically sophisticated silicon panel technology available commercially today. It delivers the best efficiency, the lowest degradation, and the best temperature performance — at a price premium that reflects those advantages.

What HJT is. HJT stands for Heterojunction Technology. It was pioneered by Sanyo (later acquired by Panasonic) under the brand name “HIT” (Heterojunction with Intrinsic Thin-layer). The “heterojunction” refers to the junction between two different types of semiconductor material within the same cell.

A standard silicon cell generates electron-hole pairs only at the single junction between the P and N layers. HJT solar panels wraps the crystalline N-type silicon core with ultra-thin layers of amorphous silicon (silicon with a disordered, non-crystalline structure). This creates multiple junctions and dramatically suppresses surface recombination — the same problem TOPCon solves with its oxide layer, but using a different material approach.

The critical manufacturing difference: amorphous silicon layers are deposited at low temperature (~200°C), versus the ~900°C processing temperatures required for TOPCon and PERC. This lower thermal budget preserves the N-type wafer’s properties and is one reason HJT cells have such exceptional temperature coefficients. It also means HJT requires different — and currently more expensive — production equipment.

Performance profile:

The temperature coefficient advantage deserves emphasis. At a typical peak operating temperature of 45°C above ambient, a PERC panel (-0.35%/°C) loses about 15.75% of its rated output to heat. An HJT panel (-0.26%/°C) loses only 11.7%. In a hot climate — Arizona, Florida, Texas, Southern California — this difference compounds year after year and significantly affects total lifetime yield.

Explore heterojunction solar panels optimized for high-temperature environments.

Brands at A1 SolarStore: REC (Alpha Series), Canadian Solar (HJT-specific product lines), Panasonic.

Bifacial panels — generating power from both sides

Bifacial is frequently listed alongside PERC, TOPCon, and HJT as if it were the same type of category. It isn’t. While those are cell architectures — technologies describing what happens inside the silicon — “bifacial” describes the physical construction of the module.

What bifacial means. A standard (monofacial) panel has an opaque white backsheet that blocks any light from reaching the rear of the cells. A bifacial panel replaces that backsheet with either a transparent backsheet or a second sheet of glass, exposing the rear of the cells to light. Any sunlight reflected off the surface below the panel — grass, gravel, concrete, snow, water — hits the back of the cells and generates additional electricity.

The extra output from the rear side is called the “bifacial gain,” and it ranges from roughly 5% to 30% depending on what’s below the panels. Ground-mounted systems on light-colored gravel or in snowy environments see the highest gains. Flush rooftop installations on dark tiles may see gains close to zero.

Most N-type panels — both TOPCon and HJT — are designed as bifacial by default. The transparent rear layer that bifaciality requires is compatible with both technologies and actually improves their efficiency by reducing recombination. HJT bifaciality can reach up to 95%, meaning the rear side generates 95% as much power per unit area as the front under equivalent illumination. TOPCon typically reaches 80–90%.

PERC-based panels can also be made bifacial, but with lower rear-side gains due to the opaque passivation layer design. This is one of the structural reasons N-type is gaining ground: the shift to N-type and the shift to bifacial are happening simultaneously, and they reinforce each other.

How the technologies compare — head to head

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Reading the numbers. The degradation gap between PERC and HJT sounds small — 0.5% vs 0.27% per year — but over 25 years it compounds into a meaningful difference in lifetime output. A PERC panel retains roughly 88% of its rated output at year 25. An HJT solar panels retains approximately 93%. On a 10 kW system, that's roughly 500 kWh per year of additional generation in year 25 from HJT — equivalent to running a typical refrigerator for over a year.

TOPCon hits a compelling middle point: it out-generates PERC by 1.5–2.5% annually in real-world conditions, costs only 10–15% more per watt, and has no LID losses. For most installations in 2026, it offers the best balance of performance and price.

Brand name decoder — what the marketing terms actually mean

One of the most confusing aspects of buying solar panels is that manufacturers don't always call their technology by its engineering name. Here's a quick reference for the branded terms you'll encounter at A1 SolarStore.

The pattern is consistent: any product name accompanied by "N-type," "Neo," or "Pro" from a major manufacturer almost certainly signals a TOPCon or HJT cell underneath. Products without these labels and at lower price points are typically PERC or older mono cells.

Which solar panel technology is right for you?

The right choice depends less on which technology is theoretically "best" and more on your installation context, budget, and goals.  Use our solar system calculator to get a personalized recommendation based on your roof and location.

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Sergey Fedorov

Co-founder & CTO

Sergey has been running A1 SolarStore since 2017 with the main idea in mind – making going solar easier for everyone. Based on a thorough market research and his personal experience, he shares his ideas on both solar industry and management related topics

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