One of the biggest advantages of bifacial solar panels is their ability to generate electricity from both sides of the module. By capturing sunlight that reaches the rear of the panel, bifacial technology can potentially produce more energy than traditional monofacial solar panels.
But how much additional electricity can bifacial solar panels actually generate?
The answer depends heavily on the installation. Factors such as panel height, surface reflectivity, spacing, tilt and shading can all influence the amount of energy produced.
What Is Bifacial Gain?
Before looking at energy production, it is important to understand the term bifacial gain.
Bifacial gain refers to the additional energy generated by the rear side of a bifacial solar panel compared with the energy generated by the front side alone.
For example, if a panel produces a certain amount of electricity from its front side and the rear contributes additional generation, that increase represents the panel's bifacial gain.
The exact gain varies between installations, meaning there is no single percentage that applies to every bifacial solar system.
Why Does Bifacial Gain Vary?
The amount of additional electricity produced by bifacial solar panels depends on how much useful sunlight reaches their rear surfaces.
Several factors can influence this.
Surface Reflectivity
The surface beneath the panels can have a significant impact.
A light-coloured or reflective surface can send more sunlight towards the rear of the module.
Dark surfaces generally absorb more sunlight, meaning less reflected light may reach the rear.
This is why the surrounding surface should be considered carefully when designing a bifacial installation.
Panel Height
The height of the panels above the ground or roof can also affect performance.
When a bifacial solar panel is raised higher, there can be more space for light to reach the rear of the module.
Greater clearance can also allow reflected sunlight to spread underneath the panels.
However, increasing the mounting height can increase structural requirements and installation costs, so it is important to find an appropriate balance.
Panel Spacing
The distance between rows and individual panels can influence how much light reaches the rear.
If panels are installed too close together, they can block or reduce the amount of reflected light available to neighbouring modules.
Increasing spacing can improve access to rear-side light, but it also requires more installation space.
For large solar farms, finding the right balance between panel density and bifacial gain is an important part of system design.
Tilt and Orientation
The angle and direction of the panels affect the amount of sunlight reaching them.
With bifacial solar panels, the design should also consider how sunlight interacts with the surface behind and around the modules.
The ideal configuration depends on the location, system type and surrounding environment.
A professional solar system design can help determine the most suitable orientation and tilt for the project.
Shading and Obstructions
Shading can reduce solar generation from both sides of a bifacial module.
Trees, buildings, mounting structures and nearby panels can all block sunlight.
The rear side should receive particular attention because objects underneath or around the modules can reduce the amount of reflected light reaching the solar cells.
Shadows should be assessed throughout the day and across different seasons when planning a system.
Ground-Mounted Bifacial Solar Panels
Ground-mounted solar installations can provide excellent conditions for bifacial technology.
The panels can be elevated above the ground, giving light access to their rear surfaces.
The ground itself can also provide reflected light.
For large-scale projects, factors such as row spacing, mounting height and ground conditions can all be optimised to increase the potential bifacial contribution.
Solar Carports
Solar carports are another application where bifacial solar panels can work particularly well.
Because the panels are elevated above parking areas, both sides of the modules can have access to light.
The surface underneath can also reflect sunlight towards the rear.
This combination can provide favourable conditions for additional energy generation.
Commercial Rooftop Systems
Commercial and industrial rooftops can also benefit from bifacial technology.
However, the mounting configuration is particularly important.
Panels installed directly against a dark roof may have limited rear-side generation. A raised mounting system and suitable roof surface can provide better conditions.
The expected energy yield should therefore be calculated based on the actual installation rather than assuming a standard bifacial gain.
How Much More Energy Can They Produce?
There is no universal figure for how much additional electricity bifacial solar panels will generate.
The potential increase depends on the specific conditions of the installation.
A well-designed system with high surface reflectivity, suitable panel clearance and minimal shading can achieve a much greater bifacial contribution than a system where the rear is heavily restricted.
This is why manufacturers' stated bifacial performance should be treated as a potential under defined conditions rather than a guaranteed increase for every project.
Measuring Bifacial Performance
When evaluating a bifacial solar system, it is useful to monitor actual energy production after installation.
Monitoring systems can provide information about electricity generation and help identify whether the installation is performing as expected.
For commercial and utility-scale systems, ongoing monitoring can be particularly valuable because small differences in energy yield can have a significant financial impact over time.
Bifaciality Factor vs Bifacial Gain
These two terms are sometimes confused, but they are not the same.
Bifaciality factor describes the relative electrical performance of the rear side of a module compared with its front side under specified test conditions.
Bifacial gain describes the additional energy generated by the rear side in an actual installation.
A module can have a high bifaciality factor, but its real-world bifacial gain will still depend on how much light reaches the rear.
How to Maximise Bifacial Energy Generation
To maximise the potential output of bifacial solar panels, consider:
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Using a suitable reflective surface.
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Providing adequate clearance beneath the panels.
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Optimising panel spacing.
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Minimising shading.
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Choosing an appropriate mounting structure.
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Optimising tilt and orientation.
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Keeping the installation clean.
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Monitoring energy production.
These factors should be considered together when designing the system.
Does More Bifacial Gain Always Mean Better Value?
Not necessarily.
Increasing bifacial gain may require additional installation space, more expensive mounting structures or other design changes.
The additional energy produced needs to be compared with the extra cost involved.
For this reason, the goal shouldn't simply be to achieve the highest possible bifacial gain. Instead, the goal should be to find the configuration that provides the best overall return on investment.
Final Thoughts
Bifacial solar panels have the potential to generate more electricity than conventional monofacial panels by making use of sunlight reaching their rear surfaces.
However, the amount of additional energy depends heavily on the installation.
Surface reflectivity, panel height, spacing, tilt, orientation and shading can all affect bifacial performance. This means careful system design is essential for getting the most from the technology.
For ground-mounted solar farms, solar carports and suitable commercial installations, bifacial panels can provide particularly strong potential.
In the next article in this series, we'll look at installing bifacial solar panels, including the best positioning, mounting systems and surface conditions for maximising their energy output.
