Bifacial Solar Panel

A bifacial solar panel is a photovoltaic module designed to generate electricity from both the front and rear sides. Unlike traditional monofacial panels, which only capture sunlight from one direction, bifacial modules absorb direct sunlight on the front and reflected or diffused light on the back. This dual-sided power generation increases total energy yield, improves performance in high-reflectivity environments, and enhances ROI in both commercial and utility-scale solar projects.

Bifacial modules are commonly paired with ground-mount systems, trackers, or high-albedo surfaces to maximize rear-side production. They are widely used in advanced system design practices and can be modeled using tools such as Solar Designing and shading engines like Shadow Analysis.

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Key Takeaways

Bifacial solar panels generate electricity from both the front and rear sides.
Rear-side performance depends heavily on albedo, height, spacing, and shading conditions.
Bifacial modules can provide 5–30% more energy than monofacial panels.
Most effective in ground-mount, tracker, and canopy applications.
Requires specialized modeling and layout tools for accurate energy forecasting.

What Is a Bifacial Solar Panel?

A bifacial solar panel is a PV module that has active solar cells exposed on both sides. The front side functions like a conventional solar panel, while the rear side captures additional irradiance bouncing from:

Soil
Concrete
Sand
Snow
White rooftops
Reflective ground coverings

This additional energy capture leads to bifacial gain, typically ranging from 5% to 30%, depending on site conditions.

Bifacial modules are often used in:

Utility-scale solar farms
Commercial rooftops
Carports and canopies
Tracker-based systems

Foundational related concepts include Albedo, Solar Irradiance, and Solar Tracker.

How Bifacial Solar Panels Work

1. Front-Side Generation

The front side absorbs direct sunlight and operates similarly to standard monocrystalline modules.

2. Rear-Side Generation

The rear side collects reflected irradiance and diffuse sky radiation.

Rear-side production depends on:

Surface reflectivity (albedo)
Mounting height
Tilt and orientation
Row spacing
Tracker configuration

See POA Irradiance for how irradiance is calculated on both sides of a module.

3. Electrical Integration

Both sides feed into a single electrical circuit within the module.

The module's performance is determined by the total combined irradiance.

4. System Optimization

Bifacial panels are modeled with specialized simulation tools to capture rear-side behavior.

Designers often use Solar Layout Optimization to place modules at heights and angles that maximize bifacial gain.

Types / Variants of Bifacial Solar Panels

1. Glass-Glass Bifacial Modules

Glass on both sides for durability, transparency, and improved rear exposure.

2. Glass-Backsheet Bifacial Modules

More flexible and lighter but slightly lower rear-side transmission.

3. Monocrystalline Bifacial Modules

Most common type; high efficiency and stability.

4. Heterojunction (HJT) Bifacial Modules

Deliver exceptional bifacial efficiency, often exceeding 90% bifaciality.

How Bifacial Panels Are Measured

1. Bifaciality Percentage

Indicates how efficient the rear side is compared to the front side.

Bifaciality (%) = Rear-Side Efficiency / Front-Side Efficiency × 100

Typical values: 70–90%.

2. Bifacial Gain

Additional energy produced due to rear-side irradiation.

Typical gain: 5%–30%, depending on albedo.

3. POA (Plane of Array) Irradiance

Measured separately for front and back sides.

See POA Irradiance.

4. Height Above Ground

Higher mounting = more rear irradiance capture.

5. Inter-Row Spacing

Wider spacing reduces shading on the rear side.

Typical Values / Ranges

Practical Guidance for Solar Designers & Installers

1. Choose surfaces with high albedo

Rear-side performance improves significantly on reflective surfaces.

See Albedo.

2. Increase ground clearance

12–24 inches minimum; utility systems may use 1–1.5 meters.

3. Model shading and rear irradiance

Use tools like Shadow Analysis for realistic shading impact.

4. Optimize row spacing

Reduce row-to-row shading to improve total output.

5. Pair with trackers

Single-axis trackers increase bifacial yield significantly.

See Solar Tracker.

6. Use accurate design tools

Platforms like Solar Designing help evaluate rear-side POA, layout, spacing, and stringing.

7. Consider structural load

Glass-glass modules weigh more and may require engineering validation.

See Mounting Structure.

Real-World Examples

1. Utility-Scale Bifacial Tracker Farm

A 150 MW project uses single-axis trackers with bifacial modules elevated 1.2 meters above ground, achieving a 12% energy gain over monofacial systems.

2. Commercial Flat Roof

A 500 kW rooftop uses raised racking and reflective roof coating, delivering 18% bifacial gain.

3. Solar Carport System

A bifacial canopy installation leverages concrete ground reflectance and angled canopy design for 15% rear-side production.