Albedo
Albedo is a measure of the reflectivity of a surface, in this case the ground around the PV plant under analysis. A value of 1.0 indicates perfect reflectivity. A value of 0 indicates complete absorption.
Typical values range from 0.15 for grass to 0.8 for fresh snow. Indicative reference values available in the scientific literature are provided below for several surface types:
| Type of surface | Typical albedo range |
|---|---|
| Asphalt | 0.07 - 0.10 |
| Gravel | 0.12 - 0.22 |
| Concrete | 0.17 - 0.31 |
| Sand | 0.15 - 0.45 |
| Bare soil (fields) | 0.12 - 0.25 |
| Grass (green) | 0.15 - 0.27 |
| Tundra | 0.18 - 0.25 |
| Dessert sand | 0.30 - 0.40 |
| Snow (old/melting) | 0.40 - 0.80 |
| Snow (fresh) | 0.80 - 0.90 |
In SolarFarmer, you can specify albedo as either a single annual value, 12 monthly values (if
your site has a strong seasonal variation). In addition, you can provide albedo data for each timestamp
of your solar resource data (*.tsv) file using a column with header Albedo.
Note that when providing albedo as part of the solar resource file, this will only be used for cloud-based calculations, and you still need to provide a monthly or annual value that will be used as a fall-back value in case there is any missing data in the albedo timeseries.
When using albedo data as part of the solar resource data, albedo will appear in the summary table together with other meteorological variables as shown below:
The monthly albedo values are averaged albedo weighted for radiation income, which are estimated considering the provided global horizontal irradiance (GHI) and surface albedo data.