Mechanism of Reflectivity Impact
Bifacial panels generate electricity from both direct sunlight (front side) and reflected light (rear side). The rear side’s efficiency depends on albedo—the proportion of light reflected by the surface beneath or around the panels. Higher albedo surfaces, such as white concrete, sand, or snow, reflect more light, increasing rear-side energy capture.
Key Factors
- Surface Type:
- High-albedo surfaces (e.g., white roofs, light-colored gravel) can boost energy production by 5–30%, depending on installation conditions.
- Low-albedo surfaces (e.g., asphalt, dark soil) provide minimal reflection, reducing rear-side gains.
- Retroreflective Behavior:
Surfaces like grass or vegetation (common in agrivoltaic setups) exhibit retroreflective properties, scattering light in varied directions. Studies show assuming grass acts as a diffuse reflector can overestimate energy yield by up to 10%, particularly for long grass.
Experimental Evidence
A study placing reflective foil under bifacial panels demonstrated a 1% increase in energy output compared to non-reflective surfaces. While modest, this highlights how even moderate reflectivity improvements contribute to gains. However, optimal surfaces (e.g., snow) achieve far higher returns.
Practical Implications
To maximize bifacial panel efficiency:
- Prioritize high-albedo surfaces during installation.
- Avoid assumptions about surface reflectance (e.g., vegetation retroreflection) without empirical data.
- Balance cost and performance: Reflective materials (e.g., foil) may offer incremental gains but require cost-benefit analysis.
In summary, reflective surfaces amplify bifacial panel output by enhancing rear-side light capture, though the actual gains depend on surface properties and installation geometry.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-reflectivity-of-surrounding-surfaces-influence-the-energy-output-of-bifacial-panels/
