24
A. Funde and A. Shah
Fig. 2.5 Plot of irradiance spectrum with snow and cloudy conditions, as measured by Kristijan
Brecl and Marko Topic, University of Ljubljana, Slovenia [7]. Normalization has been done in a
similar way, as for Fig. 2.4
components of the red and infrared i.e. of long wavelengths, in comparison with the
AM1.5 spectrum.
2.2 Albedo
The general meaning of albedo is “the proportion of the incident light or radiation
that is reflected by a surface, typically that of a planet or moon”. It is commonly
used in astronomy to describe the reflective properties of planets, satellites, and
asteroids. In our context, albedo is the fraction of sunlight reflected by the Earth’s
surface (or “ground”). Depending on the nature and composition of the ground, the
albedo changes in terms of wavelength and intensity. An albedo value of 0 indicates
complete absorption of sunlight by the ground surface and 1 indicates full reflection.
The values in between the two indicate the fraction of sunlight reflected by the ground
surface depending on its nature. Table 2.1 shows albedo values for different ground
surfaces. The highest value for albedo is for ground covered by snow.
The albedo radiation on a PV module can be received on both the front side
and the back side of a PV module. The contribution of albedo on the front side is
significant only if there are mountains or high rise terrains in the vicinity of the PV
installation. Albedo values are important in the case of “Bifacial solar PV modules”
(see Chaps. 5, 7, 9, and 10). The higher the albedo value is, for the terrain where the
modules are mounted, the more effective bifacial modules will be (Fig. 2.6).
A. Funde and A. Shah
Fig. 2.5 Plot of irradiance spectrum with snow and cloudy conditions, as measured by Kristijan
Brecl and Marko Topic, University of Ljubljana, Slovenia [7]. Normalization has been done in a
similar way, as for Fig. 2.4
components of the red and infrared i.e. of long wavelengths, in comparison with the
AM1.5 spectrum.
2.2 Albedo
The general meaning of albedo is “the proportion of the incident light or radiation
that is reflected by a surface, typically that of a planet or moon”. It is commonly
used in astronomy to describe the reflective properties of planets, satellites, and
asteroids. In our context, albedo is the fraction of sunlight reflected by the Earth’s
surface (or “ground”). Depending on the nature and composition of the ground, the
albedo changes in terms of wavelength and intensity. An albedo value of 0 indicates
complete absorption of sunlight by the ground surface and 1 indicates full reflection.
The values in between the two indicate the fraction of sunlight reflected by the ground
surface depending on its nature. Table 2.1 shows albedo values for different ground
surfaces. The highest value for albedo is for ground covered by snow.
The albedo radiation on a PV module can be received on both the front side
and the back side of a PV module. The contribution of albedo on the front side is
significant only if there are mountains or high rise terrains in the vicinity of the PV
installation. Albedo values are important in the case of “Bifacial solar PV modules”
(see Chaps. 5, 7, 9, and 10). The higher the albedo value is, for the terrain where the
modules are mounted, the more effective bifacial modules will be (Fig. 2.6).