IEC 61724-1:2021

Overview

IEC 61724-1:2021 - Photovoltaic system performance - Part 1: Monitoring specifies terminology, equipment, measurement methods, and monitoring-system classes for performance monitoring and analysis of photovoltaic (PV) systems. This second edition (2021) updates sensor and measurement requirements, introduces monitoring for bifacial systems, updates irradiance sensor and soiling measurement guidance, removes Class C monitoring systems, and refines requirements, recommendations and explanatory notes. The standard forms a normative basis for other standards and for consistent PV performance data collection.

Key Topics and Technical Requirements

• Monitoring system classification: Defines classes of PV performance monitoring systems and guidance for choosing an appropriate class for a project or asset.
• Measured parameters: Required electrical, irradiance and environmental measurements, and recommended sensor types and placements.
• Irradiance sensors: Updated requirements for global, in-plane and spectrally matched sensors; alignment, recalibration and maintenance guidance.
• Bifacial systems: New provisions for measuring rear-side irradiance, in-plane rear-side irradiance ratio and bifacial reference yields.
• Soiling measurement: Updated methods and annexed normative procedures (e.g., clean/soiled reference device pair) to quantify soiling losses using new techniques.
• Environmental monitoring: Module/backsheet temperature, ambient air temperature, wind, humidity, rainfall, snow, and soiling ratio measurement best practices.
• Tracker and concentrator systems: Monitoring and pointing-error considerations for single- and dual-axis trackers and concentrator systems.
• Electrical measurements: Inverter-level and plant-level measurement guidance to capture DC/AC energy and power for yield calculations.
• Data acquisition & quality: Sampling, timestamping, data validation, handling missing data, and quality checks to ensure trustworthy datasets.
• Calculated parameters & performance metrics: Methods for irradiation sums, energy yields, performance ratios (including temperature-corrected and bifacial PR), efficiencies, losses and indices.
• Annexes: Practical guidance on sensor attachment, soiling measurement methods, derate factors, and systems with local loads or storage.

Practical Applications and Who Uses This Standard

IEC 61724-1:2021 is essential for:

• PV asset owners and operators for consistent performance monitoring, O&M, and warranty validation.
• EPCs and system designers for selecting monitoring systems and sensor layouts.
• Monitoring equipment manufacturers to design compliant data acquisition and sensor solutions.
• Grid operators and regulators who rely on standardized performance data.
• Researchers and consulting engineers performing PV yield analysis and performance benchmarking.

Practical uses include performance verification, fault detection, estimating soiling losses, validating bifacial gains, and producing comparable performance reports.

Related Standards

• IEC 61724 series (performance monitoring and analysis) and other IEC/ISO standards that depend on reliable PV monitoring data. For full context and normative references, consult the IEC webstore for IEC 61724-1:2021.