Bifacial Solar Panel Minimum Elevation Rule
Core Question: What is the minimum ground clearance required for bifacial solar panels to capture optimal albedo gain?
Executive Technical Summary
Bifacial modules require at least 0.8 to 1.2 meters of ground clearance above the surface to allow reflected diffuse light to reach the rear cell layer evenly. Mounting flush to a roof reduces rear-side gain to near zero.
Detailed First-Principles Explanation
Albedo irradiance scatters omnidirectionally from the ground. When panels are mounted too close to the surface (< 0.5m), the center rear cells are starved of diffuse reflection due to self-shading by the frame and adjacent rows. Elevated mounting expands the rear view factor (VF), maximizing energy harvest by 8% to 22% over white gravel, snow, or membrane roofs.
Do not flush-mount bifacial panels directly on dark asphalt shingle roofs; the rear gain is negligible (1%~2%) while dual-glass weight adds structural roof strain.