When choosing solar panels for a new installation, one of the most important decisions is selecting the right type of photovoltaic technology. Traditional monofacial panels have been used successfully for many years, but bifacial solar panels have become increasingly popular as solar technology continues to develop.
Both technologies can provide reliable renewable energy, but they work slightly differently.
So, which one is better?
The answer depends on the installation, available space, system design and the amount of sunlight that can reach the rear of the panels.
What Are Monofacial Solar Panels?
Monofacial solar panels are the traditional type of photovoltaic module used in many residential, commercial and industrial installations.
They are designed primarily to generate electricity from sunlight hitting the front of the panel.
The solar cells absorb sunlight and convert it into direct-current electricity, which is then converted into usable AC electricity by an inverter.
The rear of a monofacial panel generally provides structural protection rather than actively contributing to electricity generation.
What Are Bifacial Solar Panels?
Bifacial solar panels are designed to generate electricity from both the front and rear surfaces.
The front of the panel captures direct sunlight, while the rear can capture additional reflected and scattered light.
For example, sunlight can hit the ground beneath a raised panel and reflect towards the rear of the module.
This additional light can create what is known as bifacial gain, increasing the total energy produced by the panel.
Bifacial vs Monofacial Solar Panels
| Feature | Bifacial Solar Panels | Monofacial Solar Panels |
|---|---|---|
| Front-side generation | Yes | Yes |
| Rear-side generation | Yes | Generally no |
| Potential energy yield | Higher in suitable conditions | Standard |
| Benefit from reflective surfaces | High | Limited |
| Installation requirements | More dependent on design | Generally simpler |
| Ground-mounted suitability | Excellent | Excellent |
| Suitable for standard rooftops | Depends on installation | Generally very suitable |
The biggest difference is therefore the ability of bifacial panels to make use of light reaching their rear surface.
Which Produces More Electricity?
Under suitable conditions, bifacial solar panels can produce more electricity than comparable monofacial panels.
However, the difference isn't guaranteed.
The additional generation depends on how much useful light reaches the rear of the bifacial module.
Factors such as panel height, surface reflectivity, tilt, spacing and shading can all influence the result.
A bifacial panel installed directly above a dark roof may have little opportunity to benefit from rear-side generation, while an elevated panel above a reflective surface may have considerably more potential.
The Importance of Surface Reflectivity
One of the biggest advantages of bifacial technology is its ability to utilise reflected sunlight.
Light-coloured surfaces generally reflect more sunlight than dark surfaces.
For example, a bifacial panel installed above a bright or reflective surface may receive more light on its rear than the same panel installed above a dark surface.
This makes the surrounding environment particularly important when designing a bifacial system.
Monofacial panels don't receive the same benefit because their rear side isn't normally designed to generate electricity.
Installation Differences
Monofacial panels are generally more straightforward to install because their rear side doesn't need significant exposure to sunlight.
Bifacial systems require more careful consideration.
The mounting system should provide suitable access to the rear of the modules, while panel height and spacing can influence how much reflected light reaches the solar cells.
This can make bifacial installations more dependent on careful system design.
Bifacial Solar Panels for Ground-Mounted Systems
Ground-mounted solar installations can be particularly well suited to bifacial technology.
Panels can be raised above the ground, allowing sunlight to reach their rear surfaces.
The ground underneath can also provide reflected light.
For large solar farms, optimising panel height, row spacing and ground conditions can help maximise bifacial gain across the entire installation.
Even relatively small improvements in energy generation can become significant when multiplied across a large number of modules.
Bifacial Solar Panels for Commercial Rooftops
Commercial and industrial rooftops can also benefit from bifacial technology when the installation is appropriately designed.
A suitable mounting system can provide clearance beneath the modules, allowing additional light to reach the rear.
The roof surface can also influence performance.
A reflective roof may provide more useful reflected light than a dark roof, potentially increasing the benefit of bifacial technology.
However, structural loading, wind conditions and available roof space must also be considered.
What About Residential Rooftops?
For residential installations, monofacial panels may still be the more straightforward choice.
Many residential solar panels are mounted relatively close to the roof surface, which can restrict the amount of light reaching the rear of a bifacial module.
However, bifacial panels can still be useful where the installation provides sufficient clearance and favourable surface conditions.
The best choice should therefore be based on the individual property rather than assuming that one technology is always superior.
Cost Considerations
Another important factor is the overall cost of the system.
Some bifacial solar panels can have a higher upfront cost than conventional monofacial alternatives. The mounting structure may also require additional consideration.
However, a higher initial cost doesn't necessarily mean a worse investment.
If the bifacial system generates significantly more electricity over its lifetime, the additional energy production could help offset the initial cost.
This is why it is important to compare the total cost of the system with its expected lifetime energy generation.
Durability and Construction
Many modern bifacial solar panels use glass-glass construction.
This can provide strong protection for the solar cells and make the panels suitable for long-term installations.
However, construction varies between manufacturers and models.
When comparing bifacial and monofacial panels, consider:
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Product warranty
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Performance warranty
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Glass construction
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Mechanical load rating
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Temperature performance
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Environmental resistance
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Manufacturer reputation
A high-quality monofacial panel can still provide better value than a bifacial panel that isn't suited to the installation.
Advantages of Bifacial Solar Panels
Bifacial technology offers several potential advantages:
Additional Energy Generation
The rear of the panel can capture light that would otherwise go unused.
Better Energy Yield
Under suitable conditions, bifacial panels can generate more electricity from the same installation area.
Excellent for Ground-Mounted Systems
Elevated ground-mounted installations can provide favourable conditions for rear-side generation.
Suitable for Solar Carports
The elevated structure of a solar carport allows light to reach both sides of the panels.
Advantages of Monofacial Solar Panels
Traditional monofacial panels also have important advantages:
Simpler Installation
The rear side doesn't need to be optimised for energy generation.
Wider Residential Application
They can be installed close to conventional roof surfaces without significantly affecting their intended operation.
Potentially Lower Upfront Cost
Depending on the product, monofacial panels can offer a lower initial module cost.
Proven Technology
Monofacial solar panels have been used extensively across residential, commercial and utility-scale projects.
Which Technology Is Better?
There isn't a universal answer.
Bifacial solar panels may be the better option when:
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The rear of the panels can receive plenty of light.
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Panels can be elevated above the surface.
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The surface underneath is reflective.
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Maximising energy generation is a priority.
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The additional system cost can be justified.
Monofacial panels may be better when:
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Panels are mounted very close to a dark roof.
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Rear-side light is heavily restricted.
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A simple installation is preferred.
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Keeping upfront costs low is important.
Final Verdict
Both bifacial and monofacial solar panels can be excellent choices.
The advantage of bifacial solar panels is their ability to generate electricity from both sides, potentially increasing energy production without requiring additional panel space.
However, this advantage depends heavily on the installation environment.
For ground-mounted solar farms, solar carports and certain commercial projects, bifacial technology can offer significant potential. For standard residential rooftops where the rear of the panel receives very little light, monofacial panels may remain the more practical option.
Ultimately, the best choice is the one that provides the strongest combination of energy generation, installation cost, durability and long-term value for the specific project.
In the next article in this series, we'll look at how much energy bifacial solar panels can actually generate and explore the factors that influence bifacial gain.
