2 Solar Spectra
25
Table 2.1 Albedo value of
different types of grounds,
adopted from reference [8]
Material
Albedo value
Grass
0.25
Lawn
0.18–0.23
Woods
0.05–0.18
Asphalt
0.15
Concrete, clean
0.30
Concrete, weathered
0.20
Snow, new
0.80–0.90
Snow, old
0.45–0.70
Fig. 2.6 The albedo here is ground reflection, governed by the nature of the ground surrounding
the PV panel
2.3 Indoor Lighting
The development of specific solar cell technology like amorphous silicon solar cells
(see Chap. 6)
4 to deliver significant electrical output in indoor and low-level light
conditions is likely to open up, in future, several new applications. Examples are selfpowered devices, such as intelligent sensors that communicate wirelessly, cutting
down maintenance costs and ensuring flexibility to building management systems
4 Amorphous silicon solar cells are already used to power calculator and so-called “solar watches”.
Calculators are the ideal application, because they do not need any storage. Almost all hand-held
calculators therefore use amorphous silicon solar cells. In “solar watches”, the storage problem is
a major one, preventing this application from becoming generally used.