A bifacial module (also known as a double-sided solar module) is an advanced type of photovoltaic panel that, unlike conventional modules, can absorb light from both sides. In short, it refers to a solar technology that utilizes both direct sunlight on the front side and light reflected from the surface beneath on the back side to generate electrical current.
In a nutshell: While classic solar modules have an opaque back, bifacial modules are often constructed as glass-glass designs. They also capture indirect light reflected from the ground, walls, or neighboring roofs, thereby significantly increasing the system's overall yield.
How do bifacial modules work?
The secret of bifacial solar modules lies in the double-sided activity of the solar cells and a transparent back cover (usually made of tempered glass). When sunlight hits the ground below or behind the modules, a portion of this light is reflected. In technical terms, this back-reflection is called the "albedo effect".
The specially designed back of the module absorbs these reflected light rays and converts them into additional energy. Depending on the nature of the surface beneath and the positioning of the modules, the back side can generate a significant additional yield (the so-called bifacial gain) without requiring more roof or open space.
Advantages and influencing factors at a glance
Bifacial solar modules are among the fastest-growing technologies in the PV sector and offer clear advantages:
- Higher yield on the same area: Depending on the surface beneath and the installation angle, the energy yield can be increased by 5% up to 25% compared to standard modules.
- Optimal performance in diffuse light: On cloudy days, when light is scattered from all directions, double-sided modules fully demonstrate their strengths and deliver more stable yield values.
- Robust glass-glass construction: Since most bifacial modules are equipped with glass on both sides, they feature extremely high mechanical load capacity, longevity, and excellent resistance to environmental influences.
What should you consider when planning and installing?
The additional yield from the back side depends heavily on two factors: the surface beneath and the mounting system. A bright surface (such as light gravel, flat roof membranes, or snow in winter) reflects light much better than a dark, overgrown ground. Furthermore, the modules require some clearance from the surface so that the reflected light can reach the back side optimally.
Therefore, bifacial modules are particularly efficient for elevated flat roof systems, ground-mounted systems, agri-PV projects (combining agriculture and solar), or vertically installed fence systems with an east-west orientation. For demanding B2B projects, they offer a future-proof way to maximize the economic efficiency of photovoltaic systems.