Bifacial Panels: Are They a Good Option for Urban Roofs?

Bifacial Panel Benefits

Bifacial panels can increase energy output by 10-30% compared to traditional monofacial panels, especially in urban areas with high reflectivity. This is because they can harness energy from both the front and back sides of the panel, provided that the rear side is exposed to indirect sunlight. To maximize bifacial gain, a roof with a high albedo (reflectivity) is ideal, such as those with light-colored roofing materials.

Designing for Bifacial Efficiency

To optimize bifacial panel performance on an urban roof, it’s essential to consider the roof’s design and the surrounding environment. A roof with a slight tilt (around 15°) and minimal shading can help maximize energy output. Additionally, using a reflective coating or a white roof can increase the albedo and enhance bifacial gain. In urban areas with high tree cover or nearby buildings, bifacial panels may not be as effective due to shading and reduced indirect sunlight.

Technical Considerations

When selecting bifacial panels for an urban roof, look for modules with a high bifacial ratio (typically around 80-90%) and a high transparency index (TI) to ensure maximum energy output. The TI measures the panel’s ability to transmit light from the rear side, which is critical for bifacial performance. A higher TI indicates better performance, but it may come at a higher cost.