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IEC 62805-1:2017 Measurement of Total Haze and Spectral Haze Distribution of Photovoltaic Glass
Standardized Integrating Sphere Method for PV Cover Glass Optical Characterization
Importance of Haze Measurement for Photovoltaic Glass
IEC 62805-1:2017 defines the standardized method for measuring total haze and spectral distribution of haze in PV cover glass. Haze is the percentage of transmitted light deviating more than 2.5 degrees from the incident direction. Controlled haze enhances light trapping by increasing the optical path length of near-infrared photons.
This is the first IEC 62805 series standard for PV glass metrology, covering 300 nm to 1200 nm.
PV glass with 2-5% total haze yields 1-3% module power gain versus ultra-clear glass.
Measurement Principle and Apparatus
The integrating sphere method with a light trap collects total and scattered transmitted flux. Sphere diameter: minimum 150 mm.
| Parameter | Specification | Notes |
|---|---|---|
| Wavelength range | 300 – 1200 nm | PV solar spectrum |
| Sphere diameter | >=150 mm | Reduces port errors |
| Step size | <=10 nm | Standard resolution |
| Repeatability | +/-0.1% | Statistical significance |
| Sample size | >=50 mm x 50 mm | Representative area |
Contamination can artificially elevate haze readings by 0.5-2% absolute.
Interpreting Haze Data for Module Design
Mie scattering from micron features decreases with wavelength; Rayleigh scattering follows lambda^-4. The standard guides optimization of light-trapping coatings.
Advanced texturing achieves haze exceeding 30% at 400 nm with total transmission above 91%.
Quality Control Insights
Measure at five locations per sheet, at least 20 mm from edges. A 2 degree acceptance angle difference can alter readings by 0.3-0.8%.
Frequently Asked Questions
Q1: Difference between total haze and diffuse transmittance?
A: Total haze is the ratio of diffuse to total flux above 2.5 degrees.
A: Total haze is the ratio of diffuse to total flux above 2.5 degrees.
Q2: Does haze affect IR response?
A: Yes. A 5% haze increase at 1050 nm improves EQE by 2-4%.
A: Yes. A 5% haze increase at 1050 nm improves EQE by 2-4%.
Q3: Can haze be measured on curved glass?
A: Yes, but with increased uncertainty. Measure at normal incidence.
A: Yes, but with increased uncertainty. Measure at normal incidence.
Q4: IEC 62805-1 vs ASTM D1003?
A: IEC extends to 1200 nm with spectral resolution; ASTM uses broadband visible only.
A: IEC extends to 1200 nm with spectral resolution; ASTM uses broadband visible only.
