Overview
IEC 62805-2:2017 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies standardized methods for measuring the transmittance and reflectance of glass used in photovoltaic (PV) modules. This part of the IEC 62805 series provides clear procedures and calculation methods tailored specifically for PV glass types, including ultra-clear patterned glass, anti-reflective coated (AR) glass, and transparent conductive oxide (TCO) coated glass. It focuses on delivering reproducible, comparable data across different laboratories and times.
The standard is essential for the photovoltaic industry, where the optical properties of PV glass directly impact the efficiency and performance of solar modules. By defining proper measurement conditions and calculation methods using the spectral photon irradiance, IEC 62805-2 ensures uniformity in assessing PV glass properties across the solar cell response wavelength range from approximately 280 nm to 1,250 nm.
Key Topics
-
Measurement Scope
The standard focuses exclusively on the transmittance and reflectance of glass materials used in PV modules with both specular and diffuse optical properties, within a wavelength range significant to solar cell performance.
-
Wavelength Range and Irradiance Basis
Unlike other standards that use spectral solar irradiance, IEC 62805-2 applies the spectral photon irradiance for calculations-this aligns measurement results with the actual carrier generation mechanism in solar cells.
-
Test Methodology
- Use of integrating sphere instrumentation to measure hemispherical transmittance and reflectance.
- Calibration and sample measurement procedures designed to enhance consistency and comparability.
- Defined apparatus specifications including integrating sphere type and diameter.
-
Calculation of Results
Instructions for computing effective hemispherical transmittance and reflectance weighted by photon irradiance, enabling realistic evaluation of PV glass optical performance.
-
Sample Conditioning and Preparation
Provides guidance on managing test specimens and reference standards to reduce variability.
Applications
IEC 62805-2:2017 is critical for:
-
PV Module Manufacturers
To ensure the optical components meet required specifications that maximize module efficiency.
-
Glass Producers
For developing and certifying specialized PV glass products such as anti-reflective coatings or patterned glass.
-
Testing Laboratories
To perform consistent and internationally comparable measurements of PV glass transmittance and reflectance.
-
Research and Development
Enables accurate characterization of novel glass materials or coatings designed to optimize photovoltaic performance.
-
Quality Control and Standardization
Facilitates harmonized testing practices across the global solar industry, improving product reliability and performance assessment.
Related Standards
-
IEC 62805-1:2017 – Method for measuring PV glass – Part 1: Measurement of total haze and spectral distribution of haze. Complements Part 2 by addressing the scattering properties of PV glass.
-
IEC 60904-3:2016 – Photovoltaic devices – Part 3: Measurement principles for terrestrial photovoltaic solar devices with reference spectral irradiance data.
-
IEC 62788-1-4 – Measurement procedures for materials used in photovoltaic modules – Part 1-4: Encapsulants – Measurement of optical transmittance and calculation of solar-weighted photon transmittance.
-
ISO 9050 – Glass in building – Determination of light transmittance, solar direct transmittance, and related factors. Although broader in optical scope, it provides foundational glass measurement techniques.
Conclusion
IEC 62805-2:2017 offers a rigorous, reproducible, and industry-tailored methodology for measuring the transmittance and reflectance of photovoltaic glass. Its focus on the solar cell response wavelength and the use of photon irradiance spectrum provide practical data essential for enhancing solar panel efficiency. Adoption of this standard supports uniform quality assessment and innovation in PV glass technologies, promoting improved reliability and performance in the fast-growing solar energy sector.