If you're considering whether to buy bifacial solar panels, one of the most important questions is how much electricity they can actually produce.
Bifacial solar panels have the ability to generate electricity from both the front and rear of the module. This gives them the potential to produce more energy than conventional monofacial panels, but the amount of additional electricity depends heavily on the installation and surrounding conditions.
What Is Bifacial Energy Gain?
The additional electricity generated from the rear side of a bifacial solar panel is known as bifacial gain.
The front of the panel receives direct sunlight, while the rear can capture reflected and scattered light from the surrounding environment.
This additional light can contribute to the panel's total electricity generation.
However, bifacial gain isn't a fixed percentage. It can vary considerably between different installations.
How Much More Energy Can Bifacial Panels Generate?
There isn't one figure that applies to every bifacial solar installation.
The potential additional generation depends on factors such as:
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Surface reflectivity
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Panel height
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Panel spacing
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Orientation
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Tilt angle
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Shading
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Local sunlight conditions
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Mounting arrangement
A system specifically designed to maximise rear-side exposure can potentially achieve considerably more bifacial gain than an installation where the rear of the modules receives very little useful light.
This is why expected energy production should be calculated for the specific installation rather than relying solely on a generic percentage.
Surface Reflectivity Makes a Difference
The surface underneath the panels can have a significant influence on bifacial performance.
Light-coloured and reflective surfaces can reflect more sunlight towards the rear of the modules, while darker surfaces generally absorb more of the incoming light.
Ground-mounted systems can therefore be particularly suitable for bifacial panels when the surrounding surface provides favourable reflective conditions.
Panel Height Can Affect Performance
The distance between the panels and the surface underneath them can influence how much light reaches the rear.
Elevating the panels can allow reflected sunlight to reach the rear from a wider range of angles.
This is one reason bifacial technology can be particularly attractive for:
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Ground-mounted solar
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Solar car parks
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Elevated solar structures
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Large commercial installations
However, increasing panel height can also increase mounting costs, so the potential energy benefit should be compared with the overall installation cost.
Panel Spacing Is Important
The spacing between modules can also affect bifacial energy generation.
If panels are positioned too closely together, they can block reflected and scattered light from reaching the rear of neighbouring modules.
Carefully planned spacing can allow more light to reach the back of the panels while also helping reduce unwanted shading.
This is particularly important for larger solar projects where the panel layout can be optimised during the design stage.
Orientation and Tilt
The orientation and tilt of solar panels affect how much sunlight reaches the modules.
A good system design should aim to maximise direct sunlight on the front while also providing suitable conditions for reflected light to reach the rear.
The ideal configuration will depend on the location, installation type, available space and mounting system.
There isn't a single orientation or tilt angle that is perfect for every solar installation.
Shading Can Reduce Performance
Shading can significantly reduce solar generation.
Trees, buildings, mounting structures and neighbouring panels can prevent sunlight from reaching the modules.
With bifacial systems, it's important to consider both front-side and rear-side shading. Obstructions behind the panels can reduce the amount of useful light available to the rear solar cells.
A professional site assessment can help identify potential shading issues before installation.
Where Can Bifacial Panels Generate the Most Energy?
Bifacial panels can be used across many different types of solar projects.
Ground-Mounted Solar
Ground-mounted systems can provide plenty of space beneath the modules for reflected sunlight to reach the rear surface.
Commercial Solar
Large commercial installations can benefit from carefully planned layouts and mounting systems that maximise rear-side exposure.
Solar Car Parks
Elevated solar car parks can allow light to reach both sides of the panels, making bifacial modules an attractive option for some projects.
Residential Solar
Bifacial panels can also be installed on residential properties, although the potential additional generation depends heavily on the roof surface, panel elevation and mounting arrangement.
Does a Higher Wattage Mean More Energy?
When planning to buy bifacial solar panels, it can be tempting to choose the highest-wattage panel available.
However, rated wattage is only one part of the equation.
Overall system production also depends on:
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Panel efficiency
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Bifaciality
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Number of modules
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Orientation
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Tilt
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Shading
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Rear-side exposure
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Installation conditions
A slightly lower-wattage panel may sometimes be more suitable if it has better efficiency or fits the available installation space more effectively.
How Can You Estimate Your Expected Output?
A professional solar installer can estimate the expected annual energy yield for your specific installation.
The assessment can take into account:
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Local solar irradiation
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Panel specifications
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Number of panels
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Orientation
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Tilt angle
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Shading
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Mounting configuration
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Expected bifacial gain
This provides a more realistic estimate of potential electricity generation than simply looking at the panel's maximum rated output.
Can Bifacial Panels Improve Your Solar Investment?
For suitable installations, the additional energy generated from the rear of bifacial panels can improve the overall value of a solar system.
However, the financial benefit depends on the relationship between the additional electricity generated and the total cost of the installation.
If the site provides excellent rear-side exposure, bifacial panels may offer strong long-term value. If rear-side exposure is poor, the additional benefit may be much smaller.
Conclusion
Bifacial solar panels can generate additional electricity by capturing sunlight from both sides of the module. The amount of extra energy produced depends on factors including surface reflectivity, panel height, spacing, shading, orientation and the overall system design.
If you're planning to buy bifacial solar panels, it's important to consider the complete installation rather than simply comparing panel wattages.
With suitable conditions and careful system design, bifacial technology can help maximise renewable energy generation and make better use of the available installation space.
In the next article in this series, we'll explain how to choose the right bifacial solar panels for your specific solar system.
