Overview
IEC 60891:2021 is an international standard published by the International Electrotechnical Commission (IEC) that specifies procedures for temperature and irradiance corrections to the measured I-V (current-voltage) characteristics of photovoltaic (PV) devices. This third edition replaces the 2009 version, introducing significant technical updates including improved correction procedures and enhanced guidance tailored to various PV technologies. The standard primarily supports accurate characterization of PV cell, module, and subassembly performance by correcting I-V curve measurements to reference conditions, thus ensuring consistency and reliability in PV testing and system design.
Key Topics
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Correction of I-V Characteristics:
IEC 60891:2021 outlines standardized methods to adjust I-V measurements for variations in temperature and irradiance. This adjustment is critical since PV device output is highly dependent on these environmental factors.
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Correction Procedures:
The standard introduces four correction procedures with specific applications, including a new fourth procedure specifically designed for crystalline silicon (c-Si) technologies where temperature coefficients are unknown. These procedures allow for:
- Single or multiple measured I-V curves to be corrected to different irradiance and temperature levels.
- Simultaneous correction of irradiance and temperature using two to four measured I-V curves.
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Determination of Correction Parameters:
Methods to calculate important factors such as temperature coefficients, internal series resistance, and curve correction factors are specified. Enhanced clarifications reduce uncertainty and improve measurement accuracy within these determinations.
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Series Resistance Measurement:
An informative annex provides supplementary methods for assessing internal series resistance, an essential parameter influencing I-V curve shape and ultimately the PV device’s efficiency.
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Reporting and Documentation:
Guidelines for consistent and transparent reporting of correction procedures and associated measurement data are incorporated to support repeatability and traceability in PV testing.
Applications
IEC 60891:2021 is fundamental for professionals engaged in photovoltaic device testing, module manufacturing, and system performance analysis. Practical uses include:
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Performance Verification:
Ensuring PV device outputs are comparable by correcting I-V characteristics to standard test conditions (STC), aiding in quality control and certification.
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R&D and Product Development:
Researchers and manufacturers can apply these correction procedures for accurate evaluation of new PV materials and module designs under varying environmental conditions.
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System Design and Simulation:
Accurate I-V curve corrections enable better modeling of PV system performance and energy yield prediction, supporting optimized system design and investment decisions.
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Certification Bodies and Testing Laboratories:
Adoption of IEC 60891 procedures ensures alignment with international standards, facilitating global recognition and market acceptance of test results.
Related Standards
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IEC 60904-1 (Measurement of Photovoltaic Current-Voltage Characteristics):
Specifies requirements for I-V measurement of photovoltaic devices. IEC 60891 complements it by providing correction methods to standardize these measurements.
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Other IEC 60904 series parts:
Covering additional photovoltaic performance and reliability tests, essential for comprehensive PV characterization.
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IEC 61215 (Terrestrial Photovoltaic Modules - Design Qualification and Type Approval):
Supports module qualification, often relying on accurate I-V procedures standardized in IEC 60891 and 60904 series.
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ISO/IEC Directives, Part 2:
Framework directing the preparation and drafting of IEC International Standards ensuring coherence and quality of technical publications.
Keywords: IEC 60891, photovoltaic devices, I-V characteristics, temperature correction, irradiance correction, PV testing standard, photovoltaic module, solar cell testing, series resistance measurement, PV performance evaluation, international standard, PV device characterization.
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