Albedo usual coefficients

The albedo coefficient is the fraction of global incident irradiation reflected by the ground facing a tilted plane.

The value usually admitted in urban localities is of the order of 0.14 to 0.22, and can go up to 0.8 for snow cover. The usual value is 0.2 (default in PVsyst).

Ideally, the best value for a specific situation is obtained through direct site measurement (the ratio of irradiances from a pyranometer facing downward and another measuring global horizontal irradiance).

In practice, except for vertical planes, this value is not critical, as the albedo component is relatively minor in the incident global irradiation (this contribution can be visualized in the simulation monthly results).

Moreover, for row-based monofacial systems (for example ground power plants), only the first row "sees" the albedo; the shading factor on the albedo component is (n-1)/n (where n = number of rows).

The following table gives some usual values for the albedo factor: