Overview
IEC 62788-1-7:2020 is an international standard published by the International Electrotechnical Commission (IEC) focused on measurement procedures for materials used in photovoltaic (PV) modules. Specifically, Part 1-7 addresses encapsulants-the polymer materials that surround and protect solar cells inside PV modules. This part establishes a rigorous test procedure for assessing the optical durability of encapsulants through accelerated ultraviolet (UV) exposure at elevated temperatures.
Unlike existing qualification tests such as those found in IEC 61215-2, which involve shorter UV preconditioning periods, IEC 62788-1-7 applies a more intense UV radiation dose and simulates exposure equivalent to several years of outdoor terrestrial solar radiation, using a spectrum similar to natural sunlight conditions like those in Phoenix, Arizona. This allows manufacturers and researchers to evaluate the long-term degradation rate of encapsulant optical transmittance, critical for maintaining PV module efficiency and operational lifetime.
Key Topics
- Accelerated UV Exposure Testing: Using elevated temperatures and a refined solar-like radiation spectrum to simulate multi-year weathering effects on encapsulant coupons.
- Optical Transmittance Quantification: Measurement of how polymeric encapsulants lose clarity and transparency over time, directly impacting solar cell performance.
- Comparison to IEC 61215-2: IEC 62788-1-7 offers a stronger, more representative test than the limited weeks-long UV dose in UV preconditioning test MQT 10.
- Test Specimens and Measurement Methods: Procedures for preparing representative encapsulant coupon specimens and measuring changes using spectrophotometry.
- Pass/Fail Criteria and Reporting: Guidelines to determine whether encapsulant materials meet durability requirements for PV applications, facilitating informed risk management.
- Scope Limitations: Focused on encapsulants under normal terrestrial temperatures, excluding frontsheets, backsheets, and thin coatings, which are addressed in other standards such as IEC TS 62788-2.
Applications
- Photovoltaic Module Manufacturing: Ensures the selection of encapsulant materials that maintain high optical transmittance over the operational life of PV modules, leading to better product reliability and efficiency.
- Quality Assurance and Material Qualification: Used by manufacturers and certification bodies to supplement existing module qualification protocols with long-term durability insights.
- Research & Development: Enables materials scientists and engineers to evaluate novel encapsulants’ resistance to UV degradation before scaling up commercial production.
- Climate-Specific Adaptation: Though establishing climate-specific correlation is beyond the document scope, the test method helps tailor encapsulant choice for environments with high UV stress.
- Risk Management: Quantitative degradation data supports reducing performance uncertainties of PV modules in different system configurations such as residential, utility-scale, roof or rack mounts, and tracker setups.
Related Standards
- IEC 61215-2: Terrestrial photovoltaic (PV) modules – Design qualification and type approval – Part 2, which provides initial UV preconditioning tests but with limited exposure scope.
- IEC 61730-1: Photovoltaic module safety qualification, specifying general construction requirements for PV modules.
- IEC TS 62788-1-4: Measurement procedures for encapsulants, focusing on optical transmittance and color change metrics.
- IEC TS 62788-7-2: Accelerated weathering tests for polymeric materials under environmental exposure.
- IEC TS 62788-2: Covers optical durability testing of PV module frontsheets and backsheets, complementing encapsulant testing.
- IEC TS 63126: Defines conditions for normal and high-temperature use scenarios for encapsulants in PV modules.
Keywords: IEC 62788-1-7, photovoltaic encapsulants, optical durability test, accelerated UV exposure, polymer degradation, photovoltaic module testing, solar PV material standards, IEC solar standards, PV encapsulant qualification, ultraviolet weathering test.