Viessmann Vitosol 100-FM Technical Manual page 139

Appendix
(cont.)
Selective surface
The absorber in the solar collector has a highly selective coating to
improve its efficiency. This specially applied coating enables the
absorption to be maintained at a very high level for the sunlight
spectrum that hits the absorber (approx. 94 %). The emission of
long-wave heat radiation is largely prevented. The highly selective
black chromium coating is very durable.
Radiation energy
Volume of energy transmitted by radiation
Dispersion
Interaction of radiation with matter by which the direction of the radi-
ation is altered. Total energy and wavelength remain unchanged.
VITOSOL
Vacuum
A space devoid of air
Heat transfer medium
Liquid that absorbs the available heat in the absorber of the collector
and delivers it to a consumer (heat exchanger)
Efficiency
The operating efficiency of a solar collector is the ratio of the collec-
tor output to the power input. Relevant variables are e.g. the ambient
and absorber temperatures.
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