What is TOPCon?
Tunnel Oxide Passivated Contact, the mainstream N-type cell technology offering high efficiency and low degradation.
Quick Answer
TOPCon has become the default for new mainstream UK installs, replacing PERC. Most mid-market panels quoted to UK homeowners today are N-type TOPCon, offering a strong balance of efficiency, low degradation and price. Premium back-contact options (HJT, IBC, ABC, HPBC) sit above TOPCon on efficiency.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
TOPCon Explained
TOPCon stands for Tunnel Oxide Passivated Contact. It builds on PERC by adding an ultra-thin tunnel oxide layer and a passivated contact on the rear, which reduces electron losses. Built on N-type silicon, TOPCon cells reach around 22–23% efficiency, degrade more slowly than PERC, and perform better in low light and high temperatures. As of 2026 it is the most common cell technology in new mainstream residential panels from brands like Jinko, JA Solar, Trina, DMEGC and Q CELLS.
How Does TOPCon Work in the UK?
TOPCon has become the default for new mainstream UK installs, replacing PERC. Most mid-market panels quoted to UK homeowners today are N-type TOPCon, offering a strong balance of efficiency, low degradation and price. Premium back-contact options (HJT, IBC, ABC, HPBC) sit above TOPCon on efficiency.
Frequently Asked Questions
Is TOPCon better than PERC?
Yes, generally. TOPCon is an N-type technology offering higher efficiency (around 22–23% vs 20–22%), lower annual degradation, and better performance in low light and heat. It is now the mainstream choice for new UK residential panels.
TOPCon vs HJT, which is better?
Both are high-efficiency N-type technologies. HJT has a slight edge on efficiency and temperature performance and very low degradation, but TOPCon is cheaper and more widely available. For most UK homes TOPCon offers the best balance of price and performance; HJT is a premium option.
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John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He researches every battery and inverter brand against manufacturer datasheets, MCS and Ofgem data, and feedback from the MCS-certified installers in our directory before publishing.