IEC 62790:2020

Overview

IEC 62790:2020 - "Junction boxes for photovoltaic modules - Safety requirements and tests" - specifies safety, constructional requirements and test procedures for junction boxes and enclosures mounted on photovoltaic (PV) modules up to 1 500 V DC. The standard addresses protection against electric shock, insulation, mechanical and environmental resistance, marking and technical documentation for junction boxes used on PV modules. It also covers enclosures that contain electronics for conversion, control or monitoring when mounted on PV modules (the standard excludes detailed requirements for the internal electronic circuits that are covered by other IEC standards).

Key topics and technical requirements

• Scope and ratings: Applicability to PV junction boxes up to 1 500 V DC and requirements aligned with IEC 61140:2016 (class II).
• Constructional requirements: Marking, identification, cable terminations, connectors, cable anchorage, knock-outs and general design for safe use on PV modules.
• Insulation and safety: Types of insulation (basic, supplementary, double, reinforced, functional insulation) and mandatory clearances and creepage distances for dielectric safety.
• Environmental and mechanical tests: Includes thermal cycle, damp heat, weather resistance, humidity-freeze, mechanical strength at low temperature, flammability, ball-pressure and glow-wire tests.
• Electrical tests: Dielectric strength, wet leakage current, reverse overload/current tests and added test voltage requirements for cemented joints.
• Bypass diode and reverse current: New bypass-diode thermal test and reverse overload/current test procedures (aligned with IEC 61215-2:2016 MQT 18.1).
• Materials and ageing: Resistance to corrosion, ageing, approval requirements for insulation parts (RTE/RTI or TI) and categorization of material groups.
• Ingress protection (IP): Clarified IP-test methods and related sealing requirements for long-term PV module exposure.
• Documentation & marking: Requirements for durable marking, symbol guidance (e.g., "Do not disconnect under load"), and technical documentation for conformity assessment.

Practical applications

• Ensures PV junction box safety and reliability across climates and field conditions.
• Guides design and validation of junction boxes used on rooftop and utility-scale PV modules.
• Provides test procedures for manufacturers, test laboratories and certification bodies to demonstrate compliance.
• Supports quality assurance for PV module assemblers, component suppliers and safety engineers.

Who should use this standard

• PV junction box and module manufacturers
• Electromechanical designers and R&D teams
• Independent test laboratories and certification bodies
• PV system integrators, installers and standards compliance officers

Related standards

• IEC 61140:2016 (protection against electric shock - class II)
• IEC 61215-2:2016 (MQT 18.1 bypass-diode reference)
• IEC 62930 (cabling reference replacing EN 50618)
• IEC 60068 series (environmental testing references)

Keywords: IEC 62790, junction boxes, photovoltaic modules, PV junction box safety, 1500 V DC, insulation, IP rating, thermal cycle test, bypass diode test, reverse current test.