Islanding Detection Accuracy: The standard requires that photovoltaic inverters have a high - accuracy islanding detection function. They should be able to quickly and accurately identify the occurrence of islanding within a specified time. For example, under normal operating conditions, when an islanding event occurs, the inverter should detect it within a few cycles of the grid frequency.
Response Time: Once islanding is detected, the inverter must take action to disconnect from the grid within a very short time. IEC 62116 sets strict limits on this response time, usually within milliseconds, to minimize potential risks.
Compatibility with Grid Conditions: The anti - islanding measures in the standard should be compatible with different grid conditions, including various grid voltages, frequencies, and impedance characteristics. This ensures that the inverter can function properly in different power grids around the world.
Scope of Application:
IEC 62116 has a more global scope, aiming to provide a unified international standard applicable to various countries and regions. It takes into account the general characteristics of different power grids worldwide.
GB/T 35729 is a national standard in China. It is more focused on the specific grid conditions, power grid management regulations, and the development status of the domestic photovoltaic industry in China. For example, it may have more detailed regulations on grid - connected cabinets' connection to different voltage - level grids in the Chinese power grid system, which are closely related to China's unique power grid structure.
Technical Requirements:
In terms of anti - islanding, both standards emphasize its importance. However, IEC 62116 may be more principle - based, providing general guidelines for anti - islanding test procedures. GB/T 35729 may have more specific and detailed requirements in combination with China's power grid operation experience. For instance, it may define more precisely the tolerance range of grid - connected cabinet parameters under different grid - connected scenarios in China to better adapt to the actual operation of the domestic power grid.
Regarding electrical performance requirements such as rated voltage and current, IEC 62116 gives general values applicable to a wide range of grid - connected cabinets. GB/T 35729 may adjust these values according to China's power grid voltage levels and the capacity distribution of domestic photovoltaic power generation systems. For example, in China, there are different voltage levels for urban and rural power grids, and the standard will make corresponding regulations to ensure the safe and stable operation of grid - connected cabinets.
Testing and Certification:
IEC 62116 has a set of international - recognized testing procedures for anti - islanding, which are widely adopted by testing institutions around the world. The certification based on this standard is also highly recognized globally, facilitating the international trade of photovoltaic grid - connected cabinets.
GB/T 35729 has its own testing and certification system in China. The testing institutions in China will conduct comprehensive tests on grid - connected cabinets in accordance with this standard, covering not only anti - islanding but also other aspects such as environmental adaptability in the Chinese climate conditions, which are more in line with the actual use environment in China.
Comparison with UL Standards in the United States:
Safety - Oriented Differences: UL standards in the United States often place great emphasis on safety aspects. They may have more stringent requirements for the fire - resistance, electrical insulation, and shock - protection performance of photovoltaic grid - connected cabinets. IEC 62116, while also concerned with safety, focuses more on the electrical performance and anti - islanding aspects in the context of grid connection. For example, UL standards may require grid - connected cabinets to pass more rigorous fire - endurance tests to meet the safety requirements of buildings in the United States, while IEC 62116 mainly focuses on preventing islanding - related safety risks.
Market - Driven Requirements: UL standards are closely related to the market demand in the United States. They may consider factors such as the characteristics of the US power grid market, such as the prevalence of certain grid - connected equipment and the specific needs of US consumers. IEC 62116, on the other hand, is more comprehensive in considering the global market and different power grid structures around the world. For instance, the US power grid has a high penetration rate of certain types of distributed energy resources in some regions, and UL standards may be adjusted accordingly, while IEC 62116 provides a more general framework for different regions.
Comparison with European EN Standards:
Grid - Integration Considerations: European EN standards may pay more attention to the seamless integration of photovoltaic grid - connected cabinets into the European power grid system. They may have specific requirements for grid - connected cabinets to support the grid - friendly operation of the European power grid, such as requirements for active power control and reactive power compensation to meet the needs of grid voltage and frequency regulation in Europe. IEC 62116, although also considering grid - connection, has a more general approach in this regard. For example, some EN standards may require grid - connected cabinets to be able to participate in grid - voltage regulation in a more coordinated manner in the European power grid with a high proportion of renewable energy.
Environmental and Sustainability Requirements: European standards often incorporate environmental and sustainability considerations more prominently. They may have requirements for the energy - efficiency of grid - connected cabinets during operation, as well as the recyclability of materials used in the cabinets. IEC 62116 may not be as detailed in these aspects. For instance, EN standards may stipulate specific energy - efficiency indicators for grid - connected cabinets to contribute to the overall energy - saving and emission - reduction goals in Europe, while IEC 62116 mainly focuses on the basic electrical and anti - islanding functions.
Diversified Design Requirements: The differences in standards force manufacturers to design products that can meet multiple standards. For example, if a manufacturer wants to sell its photovoltaic grid - connected cabinets in both the Chinese market and the international market, it needs to ensure that the product not only meets the requirements of GB/T 35729 but also complies with IEC 62116 and other relevant international standards. This may lead to more complex product designs, as different standards may have different requirements for components, circuit layouts, and control systems.
Increased Manufacturing Costs: To meet various standards, manufacturers may need to use different materials, production processes, and testing equipment. For instance, if a standard requires higher - quality fire - resistant materials as in some UL standards, the cost of raw materials will increase. Also, the need for additional testing to comply with multiple standards will increase testing costs, ultimately affecting the overall manufacturing cost of the product.
Barriers to Market Access: The existence of different standards can create barriers to international trade. Products that meet one standard may not necessarily meet another. For example, a photovoltaic grid - connected cabinet produced in accordance with a certain national standard may face difficulties in entering a foreign market if it does not meet the local standards. This can limit the expansion of enterprises in the international market and slow down the globalization process of the photovoltaic industry.
Incentives for Standard Harmonization: On the other hand, the differences in standards also prompt the industry to seek standard harmonization. International organizations and industry associations are working towards developing more unified international standards to facilitate international trade. The development of IEC 62116 itself is a step in this direction, aiming to provide a common international standard to reduce the impact of standard differences on trade.