Bifacial Solar Panel
A bifacial solar panel has active solar cells on both the front and rear surfaces of the module, enabling it to generate electricity from sunlight hitting both sides. In addition to direct sunlight on the front, bifacial panels capture reflected light (albedo) from the ground, mounting surface, or nearby objects on the rear.
Bifacial panels have become the dominant technology for utility-scale solar over the past several years due to their energy yield advantage at minimal additional cost.
Bifacial Energy Gain
The additional energy from the rear side is called the bifacial gain. It depends on:
- Ground albedo: The reflectivity of the surface below the panels. White gravel, light concrete, or sand (albedo 0.25–0.40) provides more rear irradiance than dark asphalt or soil (albedo 0.10–0.15). Fresh snow (albedo 0.80+) dramatically increases bifacial gain.
- Ground clearance height: Higher mounting allows more diffuse reflected light to reach the rear. Ground-mount systems (1–2m height) outperform rooftop installations.
- Row-to-row spacing: Wider spacing reduces self-shading on the rear.
Typical bifacial gain in production: 3–15%, depending on the above factors.
Bifacial vs. Monofacial
Bifacial panels have a transparent rear sheet or glass, versus opaque white backsheet for monofacial panels. Bifacial costs slightly more but the energy gain makes the LCOE lower for most utility-scale applications.
For rooftop installations, bifacial gain is limited by close panel-roof proximity (limited rear irradiance access), making the cost premium less justifiable than for ground-mount systems with high clearance.