Reference / Incidence-angle modifier, beam
Model option
Fresnel, AR coating
The Fresnel equations for glass with an anti-reflective coating, tabulated at nine angles
Inputs used: ASHRAE b₀, AR-coated glass, module.iam_angles_deg, iam.angles_deg
Method
The accepted fraction comes from a table at nine incidence angles for glass with an anti-reflective coating. The values of the table come from the Fresnel equations at two surfaces, air to a coating of refractive index 1.29 and the coating to glass of index 1.526, with the light reflected back and forth inside the coating added without interference and the two polarisations averaged. From 0° to 30°, from 30° to 50° and from 85° to 90° the fraction is interpolated linearly. On the segments between, it follows the cubic through the four nearest angles.
Settings
| Setting | Value |
|---|---|
| Refractive index of the coating | 1.29 |
| Refractive index of the glass | 1.526 |
| Accepted fraction at 0° | 1 |
| Accepted fraction at 30° | 0.99896 |
| Accepted fraction at 50° | 0.98727 |
| Accepted fraction at 60° | 0.96252 |
| Accepted fraction at 70° | 0.89157 |
| Accepted fraction at 75° | 0.81428 |
| Accepted fraction at 80° | 0.67877 |
| Accepted fraction at 85° | 0.43747 |
| Accepted fraction at 90° | 0 |
References
- PVsyst 8 help, Array incidence loss (IAM)
API
iam.kind = fresnel_ar