Mirror Reflectors: Efficiency of Glass for Sunlight Reflection

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Discussion Overview

The discussion revolves around the efficiency of glass and mirrors in reflecting sunlight, particularly in the context of a design that aims to direct sunlight onto a 30-degree inclined surface. Participants explore the properties of different materials and their implications for heat transfer and reflection angles.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Conceptual clarification

Main Points Raised

  • One participant inquires about the efficiency of glass in transferring heat after reflection from sunlight and the appropriate angle for reflecting sunlight onto an inclined surface.
  • Another participant notes that the efficiency of glass depends on its type and mentions that most commercial glass is coated to reflect infrared light, which is significant for heat retention.
  • A participant corrects their initial question, clarifying that they meant to refer to a mirror rather than glass.
  • It is suggested that high-quality scientific mirrors typically have an aluminum coating that enhances reflection, while home mirrors may have aluminum on the back, affecting how light interacts with the glass.
  • Participants discuss that both types of mirrors can achieve around 90% reflectivity for sunlight wavelengths.
  • One participant asks for guidance on the angle needed to position the mirror for optimal reflection onto a 30-degree inclined surface.
  • A later reply explains the principle of reflection, indicating that light reflects off a mirror at the same angle relative to a line normal to the surface of the mirror.

Areas of Agreement / Disagreement

Participants express varying views on the efficiency of glass versus mirrors, with some focusing on the properties of glass and others on mirror coatings. The discussion remains unresolved regarding the optimal angle for mirror placement.

Contextual Notes

Participants do not fully agree on the specific types of glass and mirrors or their respective efficiencies, and there are assumptions about the properties of materials that are not explicitly defined.

Who May Find This Useful

Individuals interested in optics, materials science, or engineering design related to solar energy applications may find this discussion relevant.

piuz98
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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...
 
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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
 
hmm...i think i made mistake in my question. its should be a mirror not a glass. thank you
 
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.
 
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
 
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.
 

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