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IEC 62920: EMC Requirements and Test Methods for PV Power Conversion Equipment
IEC 62920 | Engineering Insight Article
Key Insight: IEC 62920 fills a critical gap by providing a dedicated product EMC standard for photovoltaic power conversion equipment, enabling consistent testing across the solar industry and ensuring grid compatibility worldwide.
The Need for a PV-Specific EMC Standard
Power conversion equipment (PCE) is the heart of any solar photovoltaic (PV) power system, converting DC power from solar panels into AC power for grid injection or local loads. As PV installations have grown exponentially worldwide, so has the need for consistent electromagnetic compatibility (EMC) requirements. Prior to IEC 62920, PV system integrators had to rely on generic EMC standards that did not address the unique characteristics of PV inverters — particularly their high-power operation, switching frequencies, and grid interconnection requirements.
IEC 62920, developed by IEC TC 82 (Solar photovoltaic energy systems), establishes the minimum EMC requirements for DC to AC power conversion equipment in PV systems. The standard covers both grid-interactive (grid-connected power converters, GCPC) and stand-alone inverters, addressing single or multiple PV modules in various array configurations, including those with battery or energy storage integration.
Engineering Context: PV inverters are unique among power electronic devices because they must meet both stringent grid interconnection requirements and residential/commercial EMC limits simultaneously. A utility-scale inverter rated at 1 MW presents very different EMC challenges than a 250 W microinverter, yet both must coexist in the electromagnetic environment without causing interference.
Classification and Test Requirements
The standard classifies PCE into two environmental categories: Class A for commercial/industrial environments and Class B for residential environments. This classification determines the applicable emission limits and immunity test levels, with Class B being more stringent due to proximity to sensitive electronic equipment.
| Requirement | Class B PCE (Residential) | Class A PCE (Industrial) |
|---|---|---|
| Electrostatic Discharge (ESD) | 6 kV contact / 8 kV air | 6 kV contact / 8 kV air |
| Radiated RF Immunity | 10 V/m (80 MHz – 6 GHz) | 10 V/m (80 MHz – 6 GHz) |
| Fast Transient / Burst | 2 kV (power ports) | 2 kV (power ports) |
| Surge (line-to-line) | 1 kV | 1 kV |
| Conducted RF Immunity | 10 V (150 kHz – 80 MHz) | 10 V (150 kHz – 80 MHz) |
| Voltage Dips | 0%, 40%, 70% remaining voltage | 0%, 40%, 70% remaining voltage |
| Conducted Emission (AC port) | More stringent limits | Standard limits |
| Radiated Emission | More stringent limits | Standard limits |
Immunity Requirements: The standard specifies performance criteria A, B, and C for evaluating immunity test results. Criterion A requires normal performance during and after the test. Criterion B allows temporary degradation but requires automatic recovery. Criterion C permits function loss if it can be restored by operator intervention. For grid-connected PCE, the standard pays special attention to voltage dips and interruptions — a critical consideration since grid faults can trigger nuisance tripping if the inverter is not properly designed.
Emission Requirements: IEC 62920 establishes limits for both low-frequency emissions (harmonics and flicker) and high-frequency emissions (conducted and radiated disturbances). For low-frequency emissions up to 75 A rated current, the standard references specific harmonic and voltage change limits. For high-power PCE exceeding 75 A, alternative test methods are provided in the annexes.
Engineering Design Insight: When designing PV inverters for EMC compliance, pay special attention to the DC power port conducted emissions. The standard’s limits at DC ports are particularly important because the long DC cable runs between PV arrays and inverters can act as effective antennas, coupling common-mode noise into the surrounding environment.
Test Setup and Practical Implementation
The standard provides detailed test setup configurations for different PCE types through informative annexes. Key considerations include:
Wall-Mounted vs. Floor-Standing Units: Different setups are specified for wall-mounted PCE (common in residential installations) versus floor-standing units (typical in commercial and utility installations). The reference ground plane, cable routing, and decoupling network placement all differ between these configurations.
Power Circulation Method: For high-power PCE testing, the standard describes power circulation methods that allow testing at full rated power without requiring a full-capacity grid simulator. This significantly reduces test facility requirements and costs.
Alternative Test Methods: Annex D provides alternative test methods for high-power PCE (typically > 75 A), including clamp injection methods for conducted immunity and alternative coupling/decoupling networks. These methods enable testing of equipment that would otherwise exceed the capacity of standard EMC test equipment.
Critical Note: DC/DC converters used in PV systems are not yet covered by this edition of IEC 62920. The standard explicitly notes that these devices can cause electromagnetic interference due to conducted disturbances at DC ports, and their inclusion is anticipated in future revisions.
IEC 62920 represents a significant step forward for the PV industry by harmonizing EMC requirements across jurisdictions. For design engineers, the standard provides clear targets for emission limits and immunity levels, reducing uncertainty in the certification process and facilitating faster time-to-market for compliant products.
Frequently Asked Questions
Q1: Does IEC 62920 apply to both residential and utility-scale PV systems?
Yes. The standard covers PCE for all scales, from microinverters to multi-megawatt utility-scale installations. It provides different limits and alternative test methods appropriate for each scale, including specific provisions for high-power PCE.
Q2: Does the standard address EMC between the PV array and the inverter?
The standard focuses on the AC mains port, DC power port, and enclosure port emissions/immunity. DC/DC converters and PV modules themselves are not covered, though conducted emissions at DC ports are addressed.
Q3: How does IEC 62920 relate to CISPR 11?
IEC 62920 is a product-specific EMC standard that references and supplements CISPR 11 for PV PCE applications. It specifies PV-specific test conditions, setup configurations, and in some cases, alternative limits and methods that are more appropriate for PV equipment than the generic CISPR 11 approach.
Q4: What performance criteria are used for immunity testing of grid-connected PCE?
The standard defines three performance criteria (A, B, C) adapted for PV inverters. Criterion A requires uninterrupted operation, Criterion B allows temporary power quality degradation with automatic recovery, and Criterion C permits trip if manual restart is possible.
