HJT technology

What is HJT technology?

HJT stands for heterojunction solar cells. HJT solar cells are a combination of the best qualities of crystalline silicon and amorphous thin silicon film. A HJT solar panel is composed of three layers of photovoltaic material, a combination of the two technologies. By combining these technologies, efficiencies of 25% or more can be achieved.

This innovative idea of combining two types of silicon was developed by SANYO with the name "HIT" (Heterojunction with Intrinsic Thin-layer technology). HJT technology combines the best advantage of crystalline silicon N-type and thin film, allowing:

  • the cell efficiency is greater than 24% and the panel efficiency is greater than 22%.
  • the lowest temperature coefficient is only -0.24%.
  • there is a very low annual degradation rate of only 0.4%.
  • there are no LID & PID effects.
  • offers the highest two-sided 95%.

How is HJT cell constructed?

Differences between HJT and PERC

In the standard (PERC and N-Type) crystalline solar cells that are homogeneous devices, the p-type and n-type semiconductor layers are formed on the same base material. Heterojoint cells, on the other hand, are made by combining two different types of materials. In the case of HJT silicon, the connection is made between the crystalline and amorphous silicon materials.

HJT solar panel production

Sanyo, a pioneer of HJT technology, proposed to apply an internal amorphous layer between the enriched surfaces of amorphous and crystalline silicon. This created the famous and patented "Heterojunction Sanyo" with an "Intrinsic Thin" layer, commonly known as HIT.

The HIT structure is composed of a crystalline silicon wafer, typically n-type, inserted between the inner and opposite enriched layers of amorphous silicon, deposited on both sides. On top of this is a transparent conductive oxide (TCO). Almost all existing HJT concepts are based on this template.

Advantages of HJT solar panels


Tests and the opinion of manufacturers show that HJT panels show the highest level of utilisation of double photovoltaic cells. Bifaciality above 90% is indicated by AKKOME, for example. This means that solar panels using HJT silicon are a few percent more efficient in producing electricity at the back.

N-type technology

N-type solar cells have a higher efficiency that far exceeds the industry standard of p-type solar cells in recent years. In addition, n-type cells offer much better performance at elevated temperatures. This is of great importance in installations, because in real-life conditions the modules operate significantly above the temperatures included in the STC standards in which they are tested.

Low degradation

N-type HJT cells are also less susceptible to multiple degradation mechanisms, which, given the quality of production and product testing, translates directly into operational reliability, durability and return on investment. Only 0.4% annual degradation rate and no LID & PID effects. In addition, HJT has no risk of Hot Spots.

Double glazing technology

Glass-glass module structures are a technology that uses a glass layer on the back of the modules instead of the traditional polymer backsheet. This makes them completely non-combustible, they usually have a longer guarantee and on average they lose only 0.4% efficiency per year.

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Belinus specialises in the research, development and production of innovative ultra-efficient ultra-black solar double glazing, home battery and BIPV solutions.