Definition
Albedo is the fraction of incident solar radiation reflected by the ground surface beneath PV modules. Albedo values range from 0.05 (dark asphalt) to 0.85 (snow), critically affecting bifacial gain and rear-side energy.
Albedo Values by Surface
| Surface | Albedo |
|---|---|
| Snow (fresh) | 0.70–0.85 |
| Snow (old) | 0.40–0.60 |
| White gravel | 0.25–0.35 |
| Sand (light) | 0.30–0.40 |
| Concrete (new) | 0.30 |
| Concrete (aged) | 0.20 |
| Tan TPO roof | 0.25–0.35 |
| Wet vegetation | 0.20 |
| Dry vegetation | 0.25 |
| Black EPDM | 0.05 |
| Dark asphalt | 0.05–0.10 |
| Water | 0.05–0.10 |
Design Decisions
For bifacial ground-mount projects, the choice of ground surface materially affects yield:
- White gravel: +5–8% bifacial gain vs. vegetation.
- Concrete pad: similar to gravel.
- Painted white surface: similar to gravel.
- Sand: +3–5% over vegetation in hot climates.
Surface treatment cost ($0.10–0.50/W) often pays back via 3–5% additional bifacial gain.
Key Takeaways
- Albedo is the ground reflectance, from 0.05 (asphalt) to 0.85 (snow).
- Critical input for bifacial gain calculation.
- Use monthly profile in PVsyst for accurate modeling.
- High-albedo surfaces (gravel, concrete, sand) boost bifacial gain 5–10%.
- Site-specific measurement preferred for bifacial bankable projects.
Frequently Asked Questions
5 commonly searched questions about Albedo.
What is albedo?
The fraction of solar radiation reflected by a surface. Ranges from 0 (perfect absorber) to 1 (perfect reflector). Critical for calculating bifacial module rear-side gain.
Typical albedo values?
Snow: 0.70–0.85. White gravel: 0.25–0.35. Sand: 0.25–0.40. Concrete: 0.20–0.30. Grass: 0.15–0.25. Wet soil: 0.10. Dark asphalt: 0.05–0.10.
Why does albedo matter for solar?
Bifacial modules harvest rear-side reflected light. Higher albedo = more rear-side irradiance = higher bifacial gain (up to 25%).
Does albedo change seasonally?
Yes. Vegetation albedo varies with growth. Snow cover dramatically raises winter albedo. Use monthly albedo profiles in PVsyst for accuracy.
How is albedo measured?
Portable albedometer (paired up/down pyranometers). Site-specific measurement is the gold standard for bifacial bankable projects.
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