Bifacial Modules

What are bifacial modules?

Bifacial solar modules can produce energy from both the front and rear sides of the module. They capture sunlight directly from the front surface of the module as well as light reflected onto their rear surface from the ground, roof surface, or other surroundings. When used correctly, this increases energy production, often called rear-side gains, boost, or production boost. Module data sheets define the bifaciality factor of a module. Bifacial modules are in our module library and will display as Bifacial under the Module Type column. 

Note: PAN file uploads do not support bifacial modules. To add a new bifacial module, please send the module's spec sheet to support@HelioScope.com.

What racking types can I use with bifacial modules?

Bifacial modules currently only work with Fixed Tilt racking and Single-axis Trackers. Additionally, Fixed Tilt racking designs with Independent Tilt will now generate rear-side gains. The ability to create designs with other racking types, such as East-West, will be added at a later date. To model Bifacials for Carport structures, use Fixed Tilt racking following the instructions in this article.
 

Editing Bifacial System Settings

The Bifacial System settings can be edited in the Conditions section of HelioScope New Experience. 

Click Edit to adjust the Condition Set and adjust the Bifacial System. Toggle Bifacial Model to enable or disable rear-side gains in simulations when using bifacial modules.

Note: New Condition Sets will default to having the Enable Bifacial Model turned on. Existing Condition Sets created before bifacial modules were available in HelioScope will default to having the Enable Bifacial Model turned off. Previously, the bifacial boost workaround was to add negative soiling. This should be removed if the Bifacial Model is enabled.

Albedo

Albedo is a decimal value between 0.0 and 1.0, representing the fraction of sunlight reflected off a surface. For example, an albedo of 0.2 means 20% reflected light. Higher albedo increases light reflected onto the backside of bifacial solar panels, boosting their energy efficiency. Here are some examples of albedo values:

Albedo can be set for all months using the Set All text box. Values can also be entered individually by the months of the year. 

Note: Albedo data found in some weather files is not used for bifacial simulations in HelioScope.

Rear Mismatch Loss

Rear Mismatch Loss accounts for the non-uniform irradiance on the rear side of the module. Since voltage mismatch is not modeled directly, a value can be entered manually in the text box. The default is set to 10.0%.

Rear Shading Factor

Rear Shading Factor accounts for shading caused by mechanical structures behind the modules. Since these structures are not modeled directly, a value can be entered manually in the text box. The default is set to 5.0%.

Module Transparency

The percentage of light that passes through a bifacial module, frame, or racking structure. This light will cause additional ground irradiance, which can be reflected to the rear side and produce additional energy in a bifacial system. Note that light that passes through gaps between modules due to module spacing and frame spacing is not directly modeled, so this setting can account for it. The default is set to 0.0%.

Production Reports

When the Bifacial Model is enabled, the Production Report will include the Bifacial System details in the Condition Set section.

Additionally, the Component Characterizations will highlight which equipment in the design is bifacial, identifying them as True for bifacial modules, False for non-bifacial modules or N/A for other equipment.

You can learn more about the methodology employed when using this new feature to maintain our level of accuracy with other commonly used models in the Bifacial Modeling Accuracy Study article.