Question

Why in solar system black coloured glass are used ? list two solar devices which makes use of this property in their design

Answer 1

As black color has the property of absorbing heat so they are used in solar system.
Two solar devices are:
1) Flat plate collectors (solar collector)
2) Passive systems (solar water heater)

Answer 2

Cause of their heat absorbing property black colored gases are used 

They are used in Flat plate collectors and Passive systems