How efficient is glass at reflecting sunlight onto a 30-degree surface?

[piuz98]

I have problem in my design.
how efficient the glass will transfer heat after reflection.
The heat will purely come from sunlight.
Can anyone tell me about the efficiency of glass...
then, is it any angle to reflection of sunlight into incline area, because i am trying to reflect the sunlight with mirrow into 30 degree surface area...

 

[mgb_phys]

It depends on the glass.
Remember that most of sunlight is infrared, so you can't tell how much heat is being reflected/transmitted from simply how brigth somethign looks.

Most commercial glass for windows (especially office windows) is coated with an invisibly thin metal film to reflect infrared and so keep out heat. http://www.pilkington.com/resources/kglassdatasheet.pdf

 

[piuz98]

hmm...i think i made mistake in my question. its should be a mirror not a glass. thank you

 

[mgb_phys]

Then it depends on the coating.
High quality scientific mirrors will have a coating of aluminium on the front - the light doesn't go through the glass and so it doesn't matter what the glass is.
Mirrors at home normally have either aluminium on the back of the glass and the light goes through the glass twice.

Both are going to be typically 90% reflective over the Suns wavelength range.

 

[piuz98]

Ok, thank you for u information.
do you know which angle i need to locate the mirror if i wnat to get reflection into 30 degree incline surface...
Thank you

 

[mgb_phys]

Draw a line at 90deg to the surface of the mirror (a normal) light bounces off the mirror at the same angle to this line that it arrives.