Explained: TOPCon vs HJT – What Are The Fundamental Differences In The Solar Technologies?

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Solar power has become an integral part of the global push for sustainable energy sources. There are two solar cell technologies that have shown promise: HJT (Heterojunction Technology) and TOPCon (Tunnel Oxide Passivated Contact). They both strive to increase solar cell efficiency, but they do so in very different ways. We examine the key distinctions between TOPCon and HJT technologies in this technical column.


A tunnel oxide layer that offers passivation on the cell’s backside distinguishes TOPCon solar cells from other solar cells. This structure efficiently lowers recombination losses, enhancing cell functionality as a whole. HJT cells, on the other hand, have thin amorphous silicon (a-Si) layers on the front and back of the cell. Higher cell efficiency is a result of the better passivation and decreased contact resistance made possible by this design.


TOPCon cells typically use conventional silicon wafers as its primary building block. The inclusion of a tunnel oxide layer for passivation is the crucial component, though. Thin-film technology is used in HJT cells. They are made up of layers of amorphous silicon on top of crystalline silicon wafers, which improve passivation and lower recombination losses.

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The methods used to make these technologies vary as well. In order to create contacts, a tunnel oxide layer must be deposited, followed by a metallization procedure. A-Si layers must be deposited on both sides of HJT cells, and the existence of front and rear contacts necessitates a more involved interconnection procedure.

Both technologies have advanced significantly in terms of efficiency. Commercial cells are already attaining over 25% conversion efficiency thanks to TOPCon technology, which has demonstrated amazing efficiency advances. Higher efficiency levels have been proven by HJT technology, which frequently achieves 25% or even gets close to 24% in commercial applications.

The choice of technology is significantly influenced by cost factors. Despite their outstanding efficiency, TOPCon cells can be more expensive to produce because of the extra layer and metallization step. Due to the intricacy of production, HJT cells often have greater upfront costs. However, especially in utility-scale applications, their higher efficiency frequently makes the cost worthwhile.

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Both technologies have demonstrated outstanding performance in terms of stability and durability over time. For the creation of long-term energy, this is crucial. They are excellent for a variety of environmental circumstances because they also have low temperature coefficients.

In order to maximise the effectiveness of solar cells, TOPCon and HJT technologies represent key breakthroughs in the solar sector. Despite the impressive performance of both technologies, HJT currently has the edge in terms of efficiency. The decision between these technologies is contingent on a number of variables, including the project’s scope, budget, and performance requirements. Future developments and improvements in TOPCon and HJT technologies are anticipated to influence how solar energy is produced in the future as the solar industry develops.

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