Albedo
Albedo is a measure of the reflectivity of a surface, defined as the fraction of incoming solar radiation that is reflected back rather than absorbed. It ranges from 0 (perfect absorber, no reflection) to 1 (perfect reflector). The term comes from the Latin word for "whiteness."
In solar energy, albedo is relevant primarily for bifacial solar panels, which capture reflected light (albedo radiation) on their rear surfaces in addition to direct and diffuse irradiance on the front.
Albedo Values for Common Surfaces
| Surface | Typical Albedo |
|---|---|
| Fresh snow | 0.75–0.90 |
| White gravel / crushed rock | 0.30–0.40 |
| Light concrete | 0.25–0.35 |
| Dry sand / light soil | 0.20–0.30 |
| Grass | 0.15–0.25 |
| Dark soil | 0.10–0.15 |
| Asphalt / dark gravel | 0.05–0.10 |
| Water (low sun angle) | 0.05–0.10 |
Albedo and Bifacial Solar
For ground-mount bifacial systems, the ground surface below and between panel rows reflects irradiance onto the rear of the panels. Choosing high-albedo ground cover (white gravel, light-colored geotextile) can increase bifacial gain by 2–5% compared to dark soil or asphalt.
Some utility-scale developers now specify light-colored gravel as ground cover specifically to maximize bifacial gain, as the energy benefit often exceeds the modest additional ground treatment cost.
In SolarScope
When configuring a bifacial system in SolarScope, you can note the expected ground albedo in the project description. The AI assistant can help estimate bifacial gain based on your system configuration and ground surface.