TOPCon solar photovoltaics is rapidly becoming the global standard, driven by higher efficiency and strong market growth, but key challenges remain.
The rise of TOPCon solar photovoltaics in the global market
TOPCon solar photovoltaics, short for Tunnel Oxide Passivated Contact, has become the dominant technology in the solar sector, overtaking PERC solar cells. According to recent data, its market share jumped from 10% in 2022 to around 30% in 2023, when PERC still held 64%.
By 2024, the situation reversed, with N-type TOPCon cells surpassing 50%. Current projections suggest the technology could exceed 70% of the global market. This shift reflects a structural transformation of the solar industry, relevant not only in Europe and Asia but also in emerging markets across Africa, where efficiency and durability are critical factors for large-scale deployment.
What TOPCon technology is and how it works
TOPCon is a photovoltaic technology developed in 2013 by the Fraunhofer Institute for Solar Energy Systems ISE. It introduces two additional layers into the conventional silicon cell structure:
- a tunnel oxide layer
- a highly doped polycrystalline silicon layer
The tunnel oxide, just 1 to 2 nanometers thick, reduces surface recombination of charge carriers while allowing electrons to pass through via a tunneling effect. The polycrystalline silicon layer improves electrical conductivity and reduces transmission losses.
Why N-type TOPCon is gaining ground
Like other solar cells, TOPCon can be produced using P-type or N-type silicon. The industry is increasingly shifting toward N-type due to several advantages:
- lower power-induced degradation (PID)
- better resistance to high temperatures
- reduced sensitivity to impurities
These characteristics make N-type TOPCon particularly attractive for regions with harsh climatic conditions, including many parts of Sub-Saharan Africa.
Key advantages of TOPCon solar photovoltaics
The rapid growth of TOPCon solar photovoltaics is driven by clear technical benefits:
- Reduced recombination losses, improving overall performance
- Better charge carrier collection, thanks to low-resistance pathways
- Higher open-circuit voltage (Voc)
- Higher conversion efficiency, exceeding 26%, compared to around 23.2% for PERC
- Lower degradation rates, especially in N-type cells
Efficiency milestones and recent breakthroughs
In February 2026, a research team including scientists from Jinko Solar achieved a record efficiency of 26.66% on an industrial-scale TOPCon cell (M10 silicon wafer).
The result was made possible by improvements on both sides of the cell:
- optimized boron emitters and grid design on the front side
- a silicon-polysilicon shield on the rear side to reduce metallization-induced degradation
These innovations also increased bifaciality to 88.3%, enhancing overall energy yield.
How TOPCon differs from PERC
Compared to PERC, TOPCon manufacturing requires additional steps:
- deposition of an ultra-thin silicon oxide layer (1 to 2 nm)
- deposition of a polycrystalline silicon passivation layer (60 to 100 nm)
- phosphorus doping
These added processes increase complexity but enable significantly higher performance.
Degradation challenges still to solve
Despite its advantages, TOPCon technology still faces reliability issues.
A study by the Fraunhofer Institute for Solar Energy Systems ISE identified degradation effects linked to:
- humidity exposure
- ultraviolet radiation
Accelerated aging tests showed performance losses of up to 12% under UV exposure, followed by partial recovery after humidity freeze cycles. These findings suggest the need for more targeted testing and further technological refinement.
Silver consumption and cost pressure
One of the most critical challenges for TOPCon solar photovoltaics is its reliance on silver.
Traditionally, the technology requires 10 to 12 mg/Wp of silver, about 40 to 60% more than PERC. Silver paste alone accounts for more than 50% of the wafer-to-cell conversion cost.
Market volatility is adding pressure: after steady growth from October 2025, silver prices reached around 79 dollars per ounce, down from a peak of 116 dollars in January 2026. This uncertainty could impact module costs and the levelized cost of energy (LCOE), a key factor for solar expansion in cost-sensitive regions such as Africa.
New solutions to reduce silver use
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE have developed a low-silver TOPCon variant using just 1.1 mg/Wp.
The innovation relies on a hybrid metallization process combining:
- laser structuring
- electrochemical deposition
In this architecture:
- nickel acts as a barrier against copper diffusion
- copper provides electrical conductivity
- a minimal amount of silver protects against oxidation
Tests on industrial production lines achieved 24% efficiency and confirmed stability under IEC 61215 standards.
When low-silver TOPCon could reach the market
According to Fraunhofer researchers, nickel-copper plating could become a market standard within two to three years, provided manufacturers invest in upgrading production lines.
Beyond cost reduction, this innovation could strengthen supply chain resilience, an increasingly important factor for regions seeking energy independence, including several African economies.
FAQ: TOPCon solar photovoltaics explained
What is the main difference between TOPCon and PERC?
TOPCon adds a tunnel oxide layer and a doped polycrystalline silicon layer, reducing recombination losses and increasing efficiency to over 26%, compared to about 23.2% for PERC.
Why are N-type TOPCon cells considered better?
They use phosphorus-doped silicon, avoiding boron-oxygen recombination, which results in lower degradation and better performance.
What degradation issues affect TOPCon modules?
Some modules show sensitivity to humidity and UV exposure, with performance losses observed during accelerated aging tests.
How much silver is used in TOPCon panels?
Typically 10 to 12 mg/Wp, although new processes can reduce this to 1.1 mg/Wp.
What is the current market share of TOPCon?
It has grown from 10% in 2022 to over 50% in 2024 and is expected to exceed 70% globally by 2026.
