What spectral transmittances are available?

The spectral transmittances of various types of glass and plastics, suitable for use in collector systems, are available (Toulou kian and Dewitt 1972, Meinel and Meinel 1976), but extinction coefficients, for example, are not generally documented, although they can be calculated from available data.

What is the difference between visible transmittance and visible reflectance?

Visible transmittance (τv) and visible reflectance (ρv) refer to the ratio of the beam of visible light vertically incident on a glass surface to the incident beam of transmitted light or reflected light.

What determines the transmittance of a transparent material?

The variation of the transmittance of a "transparent" material is determined by its chemical composition, molecular structure and fabrication. The mean transmittances for visible (i.e. solar) light and for infrared radiation are given in Table 3.1.1.

What is the transmittance at normal incidence to?

The transmittance at normal incidence TO, was taken to be 0.8 in the original study, as the aim was to simulate the variation in transmittance with angle for window glass which had a film of dirt corresponding to the average dirtying over a period of one month.

What is solar energy at a window?

Solar energy at a window. In solar applications, the glazing material under consideration is always a slab or transparent (or semi-transparent) material, which acts as the aperture of the collector system.

What is the difference between visible and solar radiation?

"Solar" in this context refers to the near ultraviolet, visible and near infrared wavelength region of 300 to 2500 nm that directly reaches Earth after penetrating the atmosphere. "Visible" refers to radiation of the wavelength range of 380 to 780 nm that is capable of passing through the visual sensory organs and causing visual sensation.