Solar Photovoltaic Systems and Solar power station safety qualification Requirements for testing
IEC 61730-2:2023 is a standard published by the International Electrotechnical Commission (IEC) aimed at ensuring the safe performance of photovoltaic modules under various environmental conditions. This standard covers the design, manufacturing, and testing requirements for PV modules to ensure they do not pose a risk to personnel or property during long-term use. This article will provide a detailed overview of the main content and testing requirements of this standard.
2. Scope of the Standard
IEC 61730-2:2023 applies to all types of ground-mounted photovoltaic modules, including but not limited to monocrystalline, polycrystalline, thin-film, and other new photovoltaic materials. The standard is designed to ensure the safety of these modules when used outdoors, especially under extreme weather conditions and prolonged exposure to sunlight.
3. Testing Items
3.1 Visual Inspection
- Main Requirement: The appearance of the module should show no obvious defects such as breakage, cracking, surface tears, bending, or irregularities.
- Specific Requirements:
- Metal housing should be undamaged.
- Glass window layer should be free of cracks.
- EVA layer should not have bubbles, peeling, or detachment.
- Viewing angle should not be less than 160°.
- Thickness should meet design requirements, e.g., 17.0 mm.
3.2 Insulation Testing
- Main Requirement: The insulation performance of the module should meet safety requirements to prevent electric shock hazards from electrical faults.
- Specific Requirements:
- Clarification added for certain specially processed modules regarding the application of opposite voltages, i.e., framing with positive pressure, internal circuits with negative pressure.
- Insulation resistance should meet the minimum requirements set forth by the standard.
- Insulation withstand voltage testing should be conducted under standard conditions to ensure no breakdown occurs at high voltages.
3.3 Terminal Strength Testing
- Main Requirement: The terminals of the module should have sufficient mechanical strength to prevent breakage during installation and use.
- Specific Requirements:
- A force of 40 N should be gradually applied at a direction parallel to the module frame at the terminal box edges.
- The terminal box should withstand the force without damage or looseness.
3.4 Junction Box Strength Testing
- Main Requirement: The junction box should possess adequate mechanical strength and electrical performance to ensure safe usage under various environmental conditions.
- Specific Requirements:
- The junction box should withstand multiple mechanical impacts without damage.
- The electrical connections in the junction box should be firm and reliable to prevent looseness or short circuits.
4. Functional Testing
4.1 PV Interface and PV Side Inverter Module Testing
- Main Requirement: The photovoltaic direct drive controller should have at least one interface for PV connection and be able to detect whether the input voltage exceeds the maximum voltage allowed by the controller on the PV side.
- Specific Requirements:
- The PV side inverter module should have maximum power point tracking (MPPT) capabilities to optimize power generation efficiency.
- The interface should include reverse polarity protection and overload protection features.
4.2 Grid Interface and Grid Side Inverter Module Testing
- Main Requirement: The grid interface performance of the photovoltaic direct drive controller should meet the requirements of IEC 61727, and the grid side inverter module should be bidirectional and capable of maintaining stable bus voltage.
- Specific Requirements:
- The grid interface should withstand grid fluctuations and abnormal conditions.
- The grid side inverter module should have overvoltage and overcurrent protection features.
4.3 Energy Storage Interface and Storage Side Inverter Module Testing
- Main Requirement: The storage side inverter module of the photovoltaic direct drive controller should be able to detect whether the storage parameters match the controller and maintain stable bus voltage.
- Specific Requirements:
- The controller should be capable of communicating with the connected energy storage.
- The storage side inverter module should have bidirectional charging and discharging capabilities to smooth and suppress instantaneous shocks when switching between various operating modes.
4.4 Other Energy Interface Testing
- Main Requirement: The photovoltaic direct drive controller should have open interfaces to allow connections with other energy sources such as electric vehicles and hydrogen.
- Specific Requirements:
- The form and type of interface should be determined according to the characteristics of other connected energy sources.
- The interface should include reverse polarity protection and overload protection features.
5. Performance Testing
5.1 AC Output Interface and Corresponding VFD Function Module Testing
- Main Requirement: The photovoltaic direct drive controller should have an interface that allows variable frequency AC loads, with the form and selection based on the rated voltage and current of the connected variable frequency load.
- Specific Requirements:
- The VFD output range should be specified in the product documentation, including voltage imbalance, harmonic current, frequency offset, voltage offset, etc.
- The interface should include reverse polarity protection and overload protection features.
5.2 DC Output Interface and Corresponding Conversion Module Testing
- Main Requirement: The photovoltaic direct drive controller should have DC interface requirements based on the rated voltage and current of the connected DC loads.
- Specific Requirements:
- The interface should include reverse polarity protection and overload protection features.
- The DC conversion module should maintain stable bus voltage.
6. Collaborative Functional and Performance Testing
6.1 Communication Function
- Main Requirement: Each functional module of the photovoltaic direct drive controller should be able to communicate with the signal control center to complete specific functional instructions.
- Specific Requirements:
- The communication protocols should comply with industry standards, such as Modbus and CAN.
- Communication should be real-time and reliable, ensuring normal communication in various operating modes.
6.2 Online Switching Mode Requirements
- Main Requirement: Each functional module of the photovoltaic direct drive controller should collaborate to execute online switching between various operating modes as requested by the signal control center.
- Specific Requirements:
- No electrical faults or mechanical damage should occur during switching.
- The switching time should meet standard requirements to ensure stability and reliability of the system.
6.3 DC Bus Dynamic Response
- Main Requirement: Each functional module of the photovoltaic direct drive controller should be able to collaborate to enable the DC bus to quickly reach a new steady state when switching between various operating modes.
- Specific Requirements:
- No transient overvoltage beyond permissible limits should occur at any interface during the switching process.
- The voltage fluctuations of the DC bus should be within allowable limits to ensure normal operation of the load.
7. Environmental Adaptability Testing
7.1 Compression Testing
- Main Requirement: A fully charged battery cell or module should be crushed at a speed of (5±1) mm/s until the voltage drops to 0, the deformation reaches 30%, or a pressure of (13±0.78) kN is reached, maintaining for 10 minutes without fire or explosion.
- Specific Requirements:
- The compression direction should be perpendicular to the surface of the battery cell or module.
- Voltage and temperature changes should be recorded during compression to ensure no thermal runaway occurs under extreme conditions.
7.2 Drop Testing
- Main Requirement: A fully charged battery cell or module’s positive or negative terminal should be dropped from a height of 1.5 m onto a concrete surface once, with no fire or explosion occurring.
- Specific Requirements:
- Voltage and temperature changes should be recorded during the drop to ensure no thermal runaway occurs under impact conditions.
- The component should undergo visual inspection post-drop to ensure no physical damage.
7.3 Heating Testing
- Main Requirement: A fully charged battery cell should be heated at a rate of 5 °C/min from ambient temperature to (130±2) °C and held for 30 minutes, without fire or explosion.
- Specific Requirements:
- Voltage and temperature changes should be recorded during heating to ensure no thermal runaway occurs under high-temperature conditions.
- The heating apparatus should be in direct contact with the battery and should not be larger than the heated surface of the battery cell.
7.4 Overcharging Testing
- Main Requirement: A fully charged battery cell or module should be charged at a constant current until the voltage reaches 1.5 times the terminal charging voltage of the battery cell or for a duration of 1 hour, without fire or explosion.
- Specific Requirements:
- Voltage and temperature changes should be recorded during charging to ensure prevention of thermal runaway under overcharge conditions.
- The battery management system should be able to interrupt charging in a timely manner to prevent overcharging.
7.5 Over-discharging Testing
- Main Requirement: A fully charged battery cell or module should be discharged at a constant current until a duration of 90 minutes is reached or any individual battery cell voltage drops to 0, without fire or explosion.
- Specific Requirements:
- Voltage and temperature changes should be recorded during discharging to ensure no thermal runaway occurs under over-discharge conditions.
- The battery management system should be able to interrupt discharging in a timely manner to prevent over-discharging.
8. System Level Functional Safety Testing
8.1 Overvoltage Charging Control
- Main Requirement: Prevent overcharging and ensure the battery management system can promptly interrupt charging under overcharge conditions.
- Specific Requirements:
- Manufacturers should set a voltage protection value, and when charging reaches this protection voltage, the battery management system should issue an alarm and interrupt charging.
- IEC 62619-2017 requires one test for determination, while national standards require three tests to ensure reliability of the battery management system.
8.2 Overcurrent Charging Control
- Main Requirement: Prevent overcurrent and ensure the battery management system can take action promptly under overcurrent conditions.
- Specific Requirements:
- Manufacturers should specify the maximum continuous charging current the battery system can safely handle.
- When charging current exceeds the set charging protection value, the battery management system should detect the overcurrent and take appropriate actions to control it.
- IEC 62619-2017 requires one test for determination, while national standards require three tests to ensure reliability of the battery management system.
9. Conclusion
The IEC 61730-2:2023 standard provides detailed testing requirements and methods for the safety certification of photovoltaic modules. Through these tests, the safe performance of PV modules under various environmental conditions can be ensured, thereby providing a guarantee for the long-term stable operation of photovoltaic systems. As photovoltaic technology continues to develop, the standards are also being refined to adapt to new technologies and products. Domestic certification and inspection centers and institutions should keep pace with international developments, actively participate in international competition, and provide strong support for the healthy development of the photovoltaic industry.
Essential IEC Standards for Photovoltaic Systems: Design, Safety, and Performance Guidelines
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