The solar energy sector is undergoing rapid innovation. By 2025, two technologies — TOPCon (Tunnel Oxide Passivated Contact) and HJT (Heterojunction Technology) — are set to overtake PERC (Passivated Emitter and Rear Cell) as the new market standards. This shift is fueled by higher efficiencies, better real-world performance, and increasingly competitive pricing.

Technology Overview

TOPCon (Tunnel Oxide Passivated Contact)

TOPCon cells utilise a nanometer-thin silicon oxide layer and a polysilicon passivation layer to minimise electron recombination, enhancing efficiency.

• Mass production efficiency: 24–25%
• Lab-record efficiency: >26%
• Bifaciality: >80%
• Temperature coefficient: ~-0.30%/°C
• Upgradeability: Can retrofit PERC production lines with moderate investments.

HJT (Heterojunction Technology)

HJT cells combine a crystalline silicon wafer with thin amorphous silicon layers on both sides, resulting in high light absorption and low recombination rates.

• Mass production efficiency: 24–26.5%
• Bifaciality: >95%
• Temperature coefficient: ~-0.26%/°C (best-in-class)
• Carbon footprint: Extremely low (~366g CO₂ eq/W)
• Manufacturing: Requires new production lines but involves fewer process steps.

PERC (Passivated Emitter and Rear Cell)

PERC technology enhances efficiency by passivating the rear side of the cell to improve reflectivity and reduce recombination.

• Mass production efficiency: 23–23.4%
• Bifaciality: ~70%
• Temperature coefficient: ~-0.34%/°C

Efficiency Comparison

HJT and TOPCon technologies produce substantially better conversion efficiency than PERC-based modules. TOPCon modules have achieved a regular efficiency performance above 24% while HJT modules demonstrate higher efficiency beyond 24.5%. In contrast, most commercial PERC modules plateau around 22%. Large-scale developers together with residential installers benefit from TOPCon and HJT technologies because they gain 2%-3% more efficient energy production, which leads to enhanced power output and project profitability.

Newer technologies perform better in diverse temperature conditions and reduced lighting situations than PERC modules do. Systems adopting TOPCon or HJT technology maintain powerful energy output both during daylight hours and across different climate zones, which appeals to investors aiming at maximising long-term profits.

Conclusion: TOPCon and HJT offer a 1.5%–3 % efficiency advantage over PERC, critical for boosting system output, especially where space is limited.

Market Trends
New solar technology faces its main challenge when it comes to making it affordable. The market indicates a definite transformation has begun. The HJT solar module market saw a 2.9% price reduction across the period between November 2024 through February 2025 because manufacturers achieved improved scalability, and their supply chain operations became more mature. The prices for TOPCon modules stay fixed at US$0.26/W while maintaining a level of competition that exceeds premium PERC module costs. Both price stability and decreasing costs indicate mainstream adoption. Production increases and manufacturing scale will lead to decreasing prices for TOPCon and HJT modules, which will increase their attractiveness to the market.

Price Trends (Nov 2024–Feb 2025)

• HJT module prices dropped by 2.9%, as manufacturers optimised production and scaled operations (Source: PV InfoLink, Feb 2025).
• TOPCon modules maintained stable prices around $0.26/W, consistently outperforming premium PERC pricing.

Figure 1 Price Trends for HJT and TOPCon Modules (Nov 2024 – Feb 2025)

Major Industry Investments

• LONGi Green Energy plans to expand TOPCon capacity by 30 GW by late 2025.
• JinkoSolar is investing in over 50 GW of TOPCon production lines for their Tiger Neo series.
• Trina Solar is focusing on HJT deployment, particularly for their high-efficiency Vertex N modules.

These investments reflect strong confidence in TOPCon and HJT becoming the dominant technologies over the next few years.

Figure 2 Efficiency Improvement of Solar Cell Technologies Over Time

The Industry Is Moving On

HJT and TOPCon technology module manufacturing exist at major technology producer facilities through facility reorganisation activities. Modern solar cell technology stands as the primary priority for companies formerly running on PERC technology since competition demands these advanced developments. Leading module manufacturing firms declared their worldwide plans to establish more than 100 GW of TOPCon production facilities by late 2024 for completion by the end of 2025. Nowadays, the market swiftly adopts solar industry technological changes as soon as improved performance standards materialise at equivalent price points.

Technology and Reliability

Technology Overview

àTOPCon (Tunnel Oxide Passivated Contact)

Technical design employs nanometer-thin silicon oxide to protect the rear surface against electron recombination. The rear surface contact of silicon cells benefits from a highly conductive silicon layer. The mass production efficiency of TOPCon cells reaches 24–25 %, along with laboratory results that exceed 26%. Outperforms PERC by 2–3 percentage points.

Key Features:

·       Bifaciality >80% (vs. PERC’s 70%).

·       Temperature coefficient of -0.30%/°C (better than PERC’s -0.34%/°C).

Current PERC production lines can use this technology after straightforward system updates.

àHJT (Heterojunction)

The structure of a crystalline silicon wafer layered with amorphous silicon creates a hybrid cell formation that improves light absorption and reduces recombination events. The mass production efficiency of this technology ranges from 24–26.5%, and it shows bifaciality values exceeding 95% at measurement points.

Key Features:

·       Ultra-low temperature coefficient (-0.26%/°C).

A production setup that needs new production equipment, although it involves fewer manufacturing processes.

·       Ultra-low carbon footprint (366g CO₂ eq/W).

àPERC (Passivated Emitter and Rear Cell)

The design utilises both a rear surface protection layer and a specialised light-trapping emitter that helps decrease recombination events. Mass production efficiency levels reach 23–23.4%, which matches almost perfectly with the theoretical maximum capability of 24.5%.

Key Features:

·       Mature technology with lower manufacturing costs.

·       Bifaciality ~70% and temperature coefficient of -0.34%/°C.

Real-World Implications

For Homeowners:

·       Higher Efficiency: More electricity generation from the same roof area.

·       Long-Term Savings: Reduced electricity bills over the system's lifespan.

·       Better Performance: Improved energy production in low-light and high-temperature conditions.​

For Installers and Developers:

·       The provision of advanced technological solutions delivers unique market opportunities to clients.

·       The designed optimization lets solar power systems need fewer panels, thus minimizing both installation times and expenses.

·       The future stability of your business depends on the adaptation of industry developments and new trends.​

Advantages for Installers and Developers

For Installers:

• Higher efficiency reduces the number of modules needed, cutting installation time and costs.
• Superior performance in low-light and high-temperature conditions ensures better year-round yields.

For Developers:

• Lower degradation rates guarantee stronger project financials over 25–30 years.
• Advanced warranties offered by manufacturers (often 30 years for HJT) enhance project bankability.

Outlook: Beyond 2025

While TOPCon and HJT are poised to dominate for the next few years, next-generation technologies are already emerging:

• Tandem solar cells (e.g., perovskite + silicon) are breaking 30% efficiency barriers in lab environments.
• Perovskite solar cells alone offer ultra-light, flexible panels with promising cost advantages, though challenges like long-term stability remain.

These innovations could redefine solar efficiency standards by 2027–2030.

Conclusion

Before 2025, TOPCon and HJT technologies are expected to become the industry standard because to their increased efficiencies, improved performance in real-world scenarios, and declining costs. To stay ahead of the rapidly evolving solar business, developers, EPCs, and investors planning new solar projects will need to comprehend and embrace these technologies.