Bifacial double glass solar modules: The additional power of bifacial solar cells in photovoltaics

Regardless of whether N-type or P-type solar cells (more on this below) are used, there is a way to massively increase the efficiency of the solar modules. This is bifacial technology. In contrast to the monofacial solar cell, which only generates PV electricity by illuminating the top, the bifacial solar cell is designed so that it can generate electricity from the top and bottom. The increase in the use of light achieved in this way significantly increases the efficiency of the module.

Of course, the efficiency on the bottom is not as great as on the top, which is oriented toward sunlight. Nevertheless, the efficiency can increase by more than 19% due to the radiation on the underside, depending on the location, distance from the ground and external conditions. This means that the capacity of the entire system can be increased by between 10 and 30. For example, the performance of a module that previously delivered 290 Wp increases to 320 to 360 Wp.

When installing bifacial systems, care must be taken to ensure that they are installed at a sufficient distance from the surface underneath to allow for additional radiation. The minimum distance should be at least 40 centimeters for weakly to medium reflective surfaces such as a tiled roof or grass. However, for highly reflective surfaces (e.g. snow), the distance to the ground should be greater than 1.5 meters.

How bifacial/bifacial solar modules work – Image: Xpert.Digital

In PV technology, even the smallest discrepancies in chemical composition are responsible for large differences in efficiency and economic distribution. This can be seen, for example, when comparing P-type and N-type solar cells. Both differ in terms of their cell structure, with P-type solar cells based on being built on a positively charged silicon base. In contrast, type N solar cells are designed the other way around, because the negatively doped side serves as the base of the solar cell.

Although the first solar cell developed in the USA in 1954 was an N-type, the P-type cell became popular in the following years. The reason for this was that in the early days the modules were mainly used in space travel, where they proved to be more resilient. Only in recent years have solar cell manufacturers begun to rethink their approach, which is due to the greater performance of N-type cells. The main reason for this is the longer lifespan of these cells because, unlike the P-type, they are not threatened by the “boron-oxygen defect”. This leads to a reduction in efficiency as the operating time increases. In addition, N-type solar cells are less susceptible to metallic contamination of the silicon.

However, N-type solar cells are currently more expensive to produce, due to the decades-long focus on P-type cells. Their production led to economies of scale in the value chain, which first have to be built up in N-type production. In addition, additional steps are required in the production of N-type solar modules, which further increases costs. However, due to their higher efficiency, the share of N-type is continuously increasing and it will only be a matter of time before it replaces P-type as the dominant solar cell technology.

With the glass module with bifacial cell technology, the light is captured on both the front and back of the module. Increasing the use of light increases the efficiency of the module.

Suitable for:

• Two-surface, bifacial or bifacial solar cells – interesting information about solar modules

Bifacial / Bifacial solar modules – Image: Xpert.Digital / abriendomundo|Shutterstock.com

Bifacial solar cells have a broader application perspective due to the bifacial generation capacity and higher system efficiency and are particularly suitable for snowier areas and distributed generation systems such as roofs, open spaces, fences and sound barriers.

The cell backside efficiency can reach more than 19%, and the incident backlights can be used to improve the generation capacity of the system, with the unit area capacity increase up to 10%~30%.

More about it here:

• Bifacial/Bifacial solar modules for more efficiency and increased light output

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