Jinko Solar-Bifacial Solar Modules Explained: How Albedo and Rear-Side Gain Affect Energy Yield

Bifacial solar modules generate electricity from both their front and rear sides. Their actual energy gain depends on site conditions and system design, not only on the module’s bifaciality rating. Ground reflectivity, module height, row spacing, tilt angle and tracking configuration all influence rear-side irradiance.

What Is a Bifacial Solar Module?

A bifacial solar module is designed to receive sunlight on both the front and rear surfaces. The front side captures direct and diffuse solar irradiance, while the rear side captures reflected light from the ground and surrounding surfaces.

The additional electricity generated from the rear side is known as bifacial gain. It is usually expressed as a percentage of front-side energy production:

Total energy yield = Front-side yield × (1 + bifacial gain)

Bifacial gain is different from bifaciality. Bifaciality describes the rear-side electrical capability of a module compared with its front-side capability under defined test conditions. Bifacial gain describes the additional energy produced by the complete photovoltaic system under real operating conditions.

As a result, a module with a high bifaciality rating may not achieve a high project-level gain if the rear side receives limited irradiance. Low module clearance, narrow row spacing, dark ground and shading from structural components can all reduce the benefit.

How Albedo Affects Bifacial Energy Yield

Albedo is the proportion of sunlight reflected by a surface. A surface with low albedo absorbs more sunlight, while a surface with high albedo reflects more sunlight toward the rear of a bifacial module.

According to the SAM bifacial photovoltaic model documentation, rear-side irradiance is mainly affected by ground albedo, row-to-row spacing and ground clearance height. The same source uses 0.2 as a reasonable example for grassy ground and 0.6 as an example for snow-covered ground.

Ground condition	Relative albedo	Bifacial potential
Dark soil or dense vegetation	Low	Limited
Grassland or light soil	Moderate	Moderate
Gravel or concrete	Moderate to high	Higher
White roof surfaces or snow	High	High

Albedo also changes over time. Seasonal snow, rainfall, vegetation growth, dust and ground maintenance can alter the amount of light reflected toward the module. Therefore, annual models should use monthly or seasonal albedo values when reliable data is available.

What Determines Rear-Side Gain?

Rear-side gain depends on several interacting design parameters:

- Ground albedo

- Module height above the ground

- Row-to-row spacing

- Module tilt angle

- Tracker or fixed-tilt structure

- Ground coverage ratio

- Rear-side shading

- Structural obstructions

- Local solar resource and weather conditions

Module height affects the rear side’s view of the ground and the distribution of reflected light. Increasing height can improve rear-side exposure, but it may also increase structural costs and wind loading requirements.

Row spacing creates a similar trade-off. Wider spacing can reduce inter-row shading and provide more ground area for reflection. However, it can also increase land requirements and reduce the installed capacity per hectare.

Rear-side irradiance should also be distributed as evenly as possible. According to an NREL study on bifacial PV mismatch loss, non-uniform rear-side irradiance can create additional mismatch losses. These losses may result from nearby rows, module-level shading, tracker components or other mounting structures.

Bifacial Modules for Trackers and Fixed-Tilt Systems

Single-axis trackers

Bifacial modules are commonly considered for large utility-scale projects with single-axis tracking. A tracker changes the module’s orientation during the day, which can increase front-side energy production and alter the rear-side irradiance profile.

For tracker projects, the model should include:

- Tracker rotation limits

- Torque-tube and structural shading

- Row spacing

- Ground coverage ratio

- Rear-side irradiance during morning and afternoon periods

- Wind and mechanical loading requirements

A tracker does not automatically produce a high bifacial gain. Its value depends on the relationship between tracker geometry, ground reflectivity and rear-side shading.

Fixed-tilt systems

Fixed-tilt systems can also benefit from bifacial modules, especially when the site has moderate or high albedo. These systems are often easier to model and maintain because the module orientation remains constant.

The main design variables include module tilt, clearance height and row spacing. A fixed-tilt design may be economically attractive when tracker equipment, land constraints or maintenance requirements make tracking less suitable.

High-albedo sites

High-albedo locations can provide stronger conditions for rear-side generation. Examples include gravel-covered ground, concrete surfaces, white commercial roofs and snow-prone regions.

However, a high-albedo site does not guarantee a higher return on investment. The project model still needs to account for installation costs, structural requirements, land use, cleaning, snow management and expected degradation.

Bifacial vs. Monofacial Solar Panels

Bifacial modules can be more cost-effective than monofacial modules when the additional rear-side energy offsets the added system and design costs.

Factor	Bifacial modules	Monofacial modules
Energy collection	Front and rear sides	Front side only
Dependence on albedo	High	Low
Modeling requirements	More detailed	Simpler
Suitable sites	Open ground, trackers and reflective surfaces	Most site types
Main design concern	Rear-side irradiance and shading	Front-side irradiance

For low-albedo ground with limited module clearance, the difference between bifacial and monofacial systems may be limited. By contrast, open layouts with reflective ground and sufficient rear-side exposure can provide more significant bifacial gain.

The correct comparison should use annual energy yield, levelized cost of electricity, capital cost, operating cost and internal rate of return. Module price alone does not determine which technology is more cost-effective.

How to Model Bifacial Gain Before Procurement

A procurement model should use project-specific inputs rather than a generic bifacial gain assumption. The recommended process is:

1. Collect ground albedo data for the site.

2. Define module height, tilt angle and row spacing.

3. Select the tracker or fixed-tilt configuration.

4. Simulate front-side and rear-side irradiance.

5. Include structural shading and rear-side mismatch losses.

6. Compare annual yield, levelized cost of electricity and internal rate of return.

7. Test the result under different albedo, spacing and degradation assumptions.

The NREL bifacial irradiance model shows that rear-side irradiance is affected by ground albedo, module tilt, row shading and the restricted view of the sky. These variables should therefore be included in the energy model before the module is selected.

A simple sensitivity framework can help identify project risks:

Albedo	Module height	Row spacing	Expected rear-side potential
Low	Low	Narrow	Low
Low	High	Wide	Moderate
Moderate	Medium	Medium	Moderate
High	High	Wide	High

This table is a planning framework, not a guaranteed production result. Final estimates should be validated with site-specific weather data and an accepted photovoltaic simulation tool.

Why Choose JinkoSolar Tiger Neo for Bifacial and High-Efficiency Solar Projects?

Why JinkoSolar Tiger Neo Is a Strong Choice for Solar Projects

JinkoSolar’s Tiger Neo portfolio combines high energy yield, bifacial performance and long-term reliability.

Tiger Neo bifacial modules

The bifacial Tiger Neo series is particularly suitable for projects where the rear side can receive meaningful reflected or diffuse irradiance.

Key advantages include:

Up to 85 ± 5% bifaciality for higher rear-side energy potential
N-type TOPCon technology for stable long-term performance
Temperature coefficient of up to -0.26% per degree Celsius
30-year linear power warranty
Suitable for utility-scale trackers, fixed-tilt systems and commercial projects
Particularly relevant for sites with high albedo, elevated mounting structures or wide row spacing

These characteristics make Tiger Neo bifacial modules a strong option for utility-scale developers and EPCs that want to combine high front-side power with additional rear-side generation.

Tiger Neo 5.0 for premium rooftops

Tiger Neo 5.0 is positioned as a residential-focused module for premium homes and architecturally sensitive rooftops. It combines high power density with an all-black design that can integrate more naturally with modern, tiled and pitched roofs.