Examination of an Optical Transmittance Test for Photovoltaic Encapsulation Materials: Preprint
The optical transmittance of encapsulation materials is a key characteristic for their use in photovoltaic (PV) modules. Changes in transmittance with time in the field affect module performance, which may impact product warranties. Transmittance is important in product development, module manufacturing, and field power production (both immediate and long-term). Therefore, an international standard (IEC 62788-1-4) has recently been proposed by the Encapsulation Task-Group within the Working Group 2 (WG2) of the International Electrotechnical Commission (IEC) Technical Committee 82 (TC82) for the quantification of the optical performance of PV encapsulation materials. Existing standards, such as ASTM E903, are general and more appropriately applied to concentrated solar power than to PV. Starting from the optical transmittance measurement, the solar-weighted transmittance of photon irradiance, yellowness index (which may be used in aging studies to assess durability), and ultraviolet (UV) cut-off wavelength may all be determined using the proposed standard. The details of the proposed test are described. The results of a round-robin experiment (for five materials) conducted at seven laboratories to validate the test procedure using representative materials are also presented. For example, the Encapsulation Group actively explored the measurement requirements (wavelength range and resolution), the requirements for the spectrophotometer (including the integratingmore »
- Publication Date:
- OSTI Identifier:
- Report Number(s):
- DOE Contract Number:
- Resource Type:
- Journal Article
- Research Org:
- National Renewable Energy Laboratory (NREL), Golden, CO.
- Sponsoring Org:
- USDOE Office of Energy Efficiency and Renewable Energy Solar Energy Technologies Program
- Country of Publication:
- United States
- 14 SOLAR ENERGY; 36 MATERIALS SCIENCE PV; MATERIAL CHARACTERISTICS; QUALITY ASSURANCE; ACCELERATED STRESS TESTING; RELIABILITY; POLYMER; Solar Energy - Photovoltaics
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