Low-voltage electrical installations - Part 7-712: Requirements for special installations or locations - Solar photovoltaic (PV) power supply installations
1Key Takeaways
IEC 60364-7-712:2025 applies to electrical installations of PV systems. The equipment of a PV system, like any other item of equipment, is dealt with only so far as its selection and application in the installation is concerned. A PV installation comprises all equipment from PV modules(s) up to the connection point to …
2Expert Interpretation
This article provides an in-depth analysis of IEC 60364-7-712:2025, the third edition of the international standard for photovoltaic power generation system installation. It covers core aspects such as DC bus circuits, DCU technical requirements, and electric shock protection measures, offering professional guidance for photovoltaic system design and installation. The standard also adds key technical requirements for DC connections and energy storage system integration.
IEC 60364-7-712:2025 Standard for Photovoltaic Power Generation System Installation: Technical Analysis
The third edition of IEC 60364-7-712, published by the International Electrotechnical Commission (IEC) in 2025, is an important part of the series of standards for low-voltage electrical installations and sets forth specific technical requirements for the installation of solar photovoltaic (PV) power generation systems. This standard replaces the second edition published in 2017 and has undergone a comprehensive revision and expansion in technical content.
Standard Scope and Technical Evolution
This standard applies to the electrical installation of photovoltaic systems, covering all equipment from the photovoltaic modules to the connection points with other installed parts (such as switchboards or common power supply points). The standard explicitly includes installation requirements for energy storage systems (such as batteries) and photovoltaic installation requirements for islanded operation modes described in IEC 60364-8-82.
Compared to the second edition, the main technical changes in the third edition include: requirements for photovoltaic power plants, direct connection to battery circuits, the introduction of DC bus circuits and DCUs (DC Units). These changes reflect the rapid development of photovoltaic technology over the past eight years, especially the evolution of DC system architecture.| Version Comparison Dimensions | Second Edition (2017) | Third Edition (2025) | Technical Significance | |||||
|---|---|---|---|---|---|---|---|---|
| System Architecture | Traditional Series-Parallel Structure | Introduction of DC Bus Circuit Concept | Supports More Flexible System Design | |||||
| Energy Storage Integration | Limited Requirements | Detailed Energy Storage System Requirements | Adapting to Growing Energy Storage Demand | |||||
| Overcurrent Protection | Cables and Equipment | Overcurrent Protection Devices | Short Circuit Current Calculation | Surge Protection | DC Side Equipment | Class II Lightning Protection | Impulse Voltage Testing | |
Electrical Equipment Selection and Installation Specifications
Waving System Requirements
Chapter 712.52 sets forth detailed requirements for wiring systems, including cable type selection, current carrying capacity calculation, and conductor cross-sectional area determination. The standard particularly emphasizes the application of photovoltaic-specific cables, requiring the use of photovoltaic cables conforming to IEC 62930.
Regarding current carrying capacity calculation, the standard considers the special operating conditions of photovoltaic systems, including cable temperature rise in high-temperature environments. Annex D provides detailed calculation methods and temperature correction factors for the current carrying capacity of photovoltaic cables.
Isolation and Switching Equipment
Section 712.536 specifies isolation and switching requirements, requiring appropriate isolation measures to be provided at all locations requiring maintenance, testing, or troubleshooting. For DC systems, the standard emphasizes specific requirements for DC isolators, including arc extinguishing capability and polarity marking.
Monitoring Equipment Requirements
Section 712.537 introduces monitoring requirements, including insulation monitoring and fault current monitoring. For the DC bus circuit of IT systems, an Insulation Monitoring Device (IMD) is required to detect insulation faults to ground.
DC Bus Circuit and DCU Technical Specifications
A significant innovation of the third edition standard is the introduction of the concepts of DC bus circuit and DCU (DC Unit). A DC bus circuit is defined as a common DC circuit connecting multiple DCUs or photovoltaic strings, providing greater design flexibility for the system.
DCUs, as units defined by the series connection of the outputs of DC/DC converters, play a crucial role in modern photovoltaic systems.
The standard sets forth specific requirements for the installation, protection, and monitoring of DCUs to ensure their safe operation within the system. The standard illustrates the application of different system topologies through multiple architectural configuration examples (Figures 4 to 9), including single-string, multi-parallel string, and multi-parallel DCU string configurations, providing practical reference for designers. Grounding and Protective Conductor Requirements Section 712.54 details the requirements for grounding arrangements and protective conductors. The standard requires that all exposed conductive parts be properly grounded unless double insulation or reinforced insulation is used. For protective connection conductors, the standard requires that their cross-sectional area be able to withstand the expected fault current and provides specific calculation methods and minimum cross-sectional area requirements. Particular emphasis is placed on the coordination between DC system grounding and AC system grounding.
Verification and Testing Requirements
Section 712.6 specifies the verification requirements after installation, including:
Insulation Resistance Test: Insulation resistance testing is required for all circuits to verify their insulation integrity to ground. Table 4 of the standard provides the minimum insulation resistance threshold.
Protection Device Test: Verification of the correct function of all protection devices is required, including overcurrent protection devices, residual current protection devices, etc.
Identification Verification: Verification of the completeness and correctness of all necessary identifications is required, including circuit identification, polarity identification, warning identification, etc.
Standard Implementation Recommendations and Technical Outlook
Design Phase Considerations
In the photovoltaic system design phase, it is recommended to focus on the following aspects: System architecture selection should be based on specific application requirements, considering the advantages of DC bus circuits; equipment selection should comply with the standard reference specifications, especially DC dedicated equipment; protection coordination design should ensure selective protection and reduce the scope of fault impact.
Installation and Implementation Key Points
During installation, special attention should be paid to: avoiding mechanical damage and heat buildup during cable laying; ensuring low resistance and long-term reliability in connection quality; and guaranteeing low impedance and corrosion resistance in the grounding system.
Operation and Maintenance Management Recommendations
During the operation and maintenance phase, it is recommended to establish: a regular inspection system, including insulation resistance testing and protection function verification; a fault recording and analysis system to identify potential problems; and an update and upgrade plan to adapt to technological developments.
With the continuous development of photovoltaic technology, it is expected that future standards will further integrate new requirements such as intelligent monitoring, network security, and grid support functions, providing continuous technical support for the safe, reliable, and efficient operation of photovoltaic systems.
Practical Application Case Analysis
In a large-scale commercial rooftop photovoltaic project, the DC bus circuit architecture required by this standard was applied to achieve flexible access to multiple photovoltaic sub-arrays.
Practical Application Case Analysis
In a large-scale commercial rooftop photovoltaic project, the DC bus circuit architecture required by this standard was applied to achieve flexible access to multiple photovoltaic sub-arrays.