What Is a Bifacial Solar Panel?

What Is a Bifacial Solar Panel?

A bifacial solar panel is a photovoltaic module that generates electricity from both its front and rear sides. By capturing reflected sunlight from the ground, roof, or surrounding surfaces, bifacial panels can produce more energy than traditional single-sided solar panels.

The first bifacial installation I inspected looked wrong.

The panels appeared almost transparent. Standing beneath the array, I could see daylight passing between the cells. The installer, working on a commercial carport in Colorado, simply smiled and asked:

“Have you ever seen solar panels that work from both sides?”

At the time, many people still viewed bifacial technology as a laboratory experiment.

A decade later, it has become one of the fastest-growing technologies in utility-scale solar projects.

Yet most homeowners still ask the same question.

What exactly makes a solar panel bifacial?

The answer starts with light.

But it does not end there.

How Does a Bifacial Solar Panel Work?

Conventional solar panels absorb sunlight only from the front.

The rear side is usually covered by an opaque backsheet.

Bifacial modules replace that backsheet with transparent glass or transparent materials.

This allows the rear cells to capture reflected sunlight.

Sources of reflected light include:

• White roofs.
• Concrete surfaces.
• Snow.
• Sand.
• Water.
• Light-colored gravel.

The National Renewable Energy Laboratory has reported that bifacial modules can increase energy production depending on installation conditions and surface reflectivity.

Source:

https://www.nrel.gov

The panel does not create additional sunlight.

It simply uses light that traditional panels ignore.

Why the Back Side Matters

Several years ago, I visited a commercial solar project built over white gravel.

The rear side of the panels was producing measurable energy throughout the afternoon.

The installer showed me the monitoring data.

The rear contribution reached nearly 12%.

Standing underneath the array, the concept suddenly became very practical.

Sunlight strikes the ground.

The ground reflects light.

The panel collects both.

Simple.

Yet surprisingly effective.

Energy Gain From Bifacial Technology

The additional output varies.

Surface conditions matter enormously.

According to the International Energy Agency Photovoltaic Power Systems Programme, bifacial modules may deliver energy gains ranging from approximately 5% to over 20%.

Source:

https://iea-pvps.org

Typical energy gains:

Installation Surface	Estimated Gain
Grass	5–8%
Concrete	8–12%
White membrane roof	10–15%
Snow-covered ground	15–30%
White gravel	10–20%

The numbers change.

The location changes.

The ground matters almost as much as the panel itself.

Construction of a Bifacial Solar Panel

Most bifacial panels use:

• Glass-glass construction.
• Transparent back layers.
• Dual-sided cells.
• Frameless or framed designs.

Unlike traditional modules, both surfaces remain active.

The rear side usually produces less electricity than the front.

Manufacturers often specify rear-side output as a percentage.

Typical rear-side efficiency ranges between 65% and 90% of front-side performance.

Typical Bifacial Module Structure

Component	Function
Front glass	Protects front cells
Solar cells	Generate electricity
Rear glass	Allows rear illumination
Frame	Structural support
Junction box	Electrical connection

Bifacial vs Monofacial Solar Panels

Many customers ask whether bifacial modules are always better.

The answer depends on the installation.

Feature	Bifacial Panel	Monofacial Panel
Front generation	Yes	Yes
Rear generation	Yes	No
Energy yield	Higher potential	Standard
Installation cost	Slightly higher	Lower
Mounting height	More important	Less critical
Ground reflection	Important	Minimal effect

During a warehouse project in Texas, the installer selected conventional modules because the roof offered almost no rear exposure.

The extra cost of bifacial panels would have delivered little benefit.

Technology must fit the environment.

Not the other way around.

Installation Conditions Matter

Bifacial panels work best when:

• Elevated above surfaces.
• Installed over reflective ground.
• Positioned with adequate spacing.
• Free from rear obstructions.

The National Renewable Energy Laboratory has published extensive research showing that module height and albedo strongly influence bifacial performance.

Source:

https://www.nrel.gov

Albedo refers to reflected light.

Fresh snow reflects far more sunlight than dark asphalt.

This explains why northern installations sometimes achieve surprisingly high gains during winter.

High-Albedo Surfaces

• White roofing.
• Concrete.
• Snow.
• Sand.
• White gravel.

Dark surfaces produce less reflected energy.

Real Experiences From Field Projects

The first utility-scale bifacial system I inspected stood several feet above the ground.

Walking beneath the rows felt unusual.

The rear glass remained visible.

The monitoring system showed rear-side contribution every afternoon.

Several observations stayed with me:

• Dust affected both sides.
• Ground conditions mattered.
• Panel spacing became critical.
• Maintenance crews cleaned both surfaces.

One technician joked:

“Now we have twice as much glass to wash.”

He was not entirely wrong.

Are Bifacial Solar Panels Worth It?

The answer depends on three questions:

1. Is reflected light available?
2. Can the panels be elevated?
3. Does additional energy justify the cost?

For utility projects, the answer is increasingly yes.

For residential roofs, the answer varies.

Flat white roofs often perform better.

Dark shingle roofs may see smaller gains.

Several commercial developers I have spoken with now specify bifacial modules as their default option.

The market itself has begun answering the question.

Author Experience

Michael Turner has spent more than twelve years working with photovoltaic products, solar module evaluations, field inspections, and commercial solar projects.

Professional experience includes:

• Product testing.
• Performance analysis.
• Solar farm inspections.
• Module reliability evaluations.
• Commercial and RV solar systems.

Many examples in this article come directly from field visits, commercial projects, and conversations with installers rather than laboratory simulations.

FAQ About What Is a Bifacial Solar Panel?

What is a bifacial solar panel?

A bifacial solar panel generates electricity from both the front and rear sides.

How much more energy do bifacial panels produce?

Depending on installation conditions, gains may range from 5% to over 20%.

Do bifacial panels work on residential roofs?

Yes, but performance depends on roof color, mounting height, and rear exposure.

Are bifacial panels more expensive?

They generally cost more than conventional modules, although the energy gain may offset the difference.

Do bifacial panels require special maintenance?

They require similar maintenance but both sides may need cleaning.

Visit product page:Flexible Solar Panel

Final Thoughts

People searching what is a bifacial solar panel often expect a technical definition.

After walking beneath large commercial arrays and watching rear-side production appear on monitoring screens, I would describe them differently.

Traditional solar panels look upward.

Bifacial panels pay attention to what happens underneath.

The ground becomes part of the system.

The roof becomes part of the system.

Even snow suddenly has value.

The panel itself remains familiar.

The perspective changes.

And sometimes, that additional perspective produces more electricity than people expect.