Bifacial modules or how to maximize production from PV installations

Anyone who decides to install a photovoltaic system wants to get as much electricity as possible from the investment. An easy way to increase electricity production is to choose the right photovoltaic modules – bifacial modules!

Bifacial modules – definition

Bifacial modules are those that, in addition to the front, have a bottom active part of the module, which is the one that produces electricity from reflected light. The production from the underside of the panel is not included in the nominal power. In addition, the design uses two sheets of tempered glass ( Glass-Glass technology), so the module guarantees the highest degree of fire safety, as confirmed by the TUV Class A Certificate.

“These are double-sided active photovoltaic panels based on a p+-n-n+ heterojunction silicon cell structure, made with internal thin layers of amorphous silicon. With this technology, more photons reach the panel, so the energy produced is greater than that obtained from traditional, single-sided panels, by up to 30%.”

– textbook Photovoltaics AGH 2021 publication.

How do you determine how much light a surface will reflect?

The ability of a surface to reflect light is determined by its albedo coefficient. The brighter the surface, the better it reflects light and more light will reach the underside of the module.

Double the power – how does bifacial module technology work?

Bifacial modules are an innovative solution in the field of photovoltaics, which allows to increase the efficiency of electricity generation compared to traditional solar panels. With bifacial panels, in addition to absorbing solar radiation falling directly on the top surface, it is also possible to use solar energy reflected from the ground, roof or snow. By using special materials, a bifacial module can generate additional electricity through its underside using reflected sunlight.

According to a study conducted by the German Solar Energy Association (Bundesverband Solarwirtschaft e.V.), bifacial modules can achieve efficiencies up to 30% higher than traditional solar panels. What’s more, the results of the study show that bifacial modules that were mounted horizontally on the roofs of flat buildings had a 10% higher electricity generation efficiency compared to single-sided solar panels [1].

The innovation and remarkable efficiency of bifacial modules has gained recognition in the renewable energy market, which contributes to the increasing popularity of this technology.

Bifacial modules and changing weather conditions – what benefits do they bring?

Bifacial modules, thanks to their design, are less affected by changing weather conditions than traditional solar panels. Research conducted by the National Renewable Energy Laboratory (NREL) shows that compared to single-sided photovoltaic panels, bifacial modules perform better in more difficult weather conditions, such as overcast, rainy or snowy conditions. This is due to the fact that the bifacial panel is able to take advantage of solar radiation reflected by cloud or snow cover, which increases the amount of sunlight absorbed.

The benefits of using bifacial modules in harsher weather conditions are particularly important in the context of the increasing number of PV installations in areas with different climatic conditions. Studies conducted by NREL show that when bifacial panels are installed in areas with poor sunlight, such as in the northern regions of Europe, the efficiency of electricity generation can increase by 15-20% [2].

Increased resistance to changing weather conditions is one of the key advantages of bifacial modules, which is an advantage over traditional photovoltaic panels. Thanks to the use of this technology, photovoltaic installations are more stable and efficient, which positively affects the efficiency of electricity generation.

Bifacial modules only for farms?

It is a well-established belief that bifacial photovoltaic panels are suitable only for ground installations. In practice, one encounters installations mounted on roofs as well. The brighter the roof covering, the better the albedo coefficient, and thus the higher efficiency of the modules.

Example of a bifacial module – Bauer Solar (BS-385-M6HBB-GG) 385 W:

Sources:

1. “Bifacial PV systems: Latest results from system to cell level measurements and field tests”, authors: P. Helm, M. Glatthaar, J. Wüst, A. Meyer, H. F. Schönecker
2. “Bifacial Solar Photovoltaic Technology and Applications,” authors: S. A. Kalogirou, L. G. Tsoutsos.