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CrOSS-Mating OF PV connectors

Why cross-connections put your PV project at risk

Internal contact technology is vastly different — minimize your risk by only mating connectors from the same manufacturer. Quality components and expert service are critical factors for a PV plant’s profitability and safety. Understanding the technical impacts and respective regulations is essential for installing and connecting a PV system.

It’s best to play it safe and choose quality components from one manufacturer because there is no international product standard for the design and technology of photovoltaic connectors. Each manufacturer has its own specification and specialized plug-in face, contact technology, material composition, insulation, and production processes.

While many manufacturers claim their components are “Stäubli compatible” or pluggable/connectable with MC4, we strongly support international standards and local regulations prohibiting coupling connectors from different manufacturers. Cross-connections and cross-mating components are not recommended and may lead to severe, costly damage.

Our experience managing PV incidents for more than 20 years and numerous studies show that cross-mating connectors can lead to incalculable technical and legal risks. Studies conducted by SolarBankabilityTÜV Rheinland, a group of international scientists, and the  IEA PVPS report on “Quantification of Technical Risks in PV Power" unequivocally state that cross-mating different connector brands significantly increase the technical and legal risk of a PV system.

Cross-connections are frequently identified as the root cause of connector failures, power loss, and unnecessary safety hazards. At worst, this damage may even lead to a fire. Consequently, these incidents negatively impact the return on investment (ROI) and the levelized cost of energy (LCOE).

Factors that can causetechnical incompatibility:

  • Low-quality technology and product material
  • Discrepancies in the production process and quality standards
  • Lack of alignment in tolerance zones to ensure tight and sufficiently high contact forces
  • Lack of material chemical compatibility (including production and auxiliary materials)
  • Changes in the production process without consideration of possible interactions
  • Disregard for official certification standards awarded to compliant manufacturers

Consequences of cross-connections

International standards

The legal basis, which excludes cross-connections:

  • Product norms (IEC 62852 (EN62852)) and UL 6703 product norm resp. UL 1703 module norm
  • Installation norms and local regulations
  • Assembly instructions of the manufacturer

Currently, valid PV standards (IEC 60364-7-712:2017; E343181) state that “male and female connectors […] shall be of the same type from the same manufacturer” and that UL certification for connectors only applies if products from the same product family have been mated.

For quality and safety reasons, Stäubli dissociates itself from cross-connecting components of 3rd party suppliers, being advertised as “MC4 compatible”. We assess the cross-connection of components from different manufacturers as a risk for safe use.

We further disclaim any participation in tests from independent test institutes that are misleading and wrongly indicate compatibility. We also consider the efforts from third-party suppliers to verify their connector product by an independent third-party as “Stäubli/MC4 compatible” to be inappropriate and not beneficial to the PV industry. We have not recognized any products from third-party suppliers as being compatible with the Original MC4 product portfolio and do not intend to do so in the future.

No certification

There is no compatibility and no (product) certification for a cross-connection. There are different norms on this topic: Product norm for connectors the IEC 62852 (EN62852). For instance, if a plug connector from manufacturer A is connected with a socket connector from manufacturer B, the certification is not valid anymore. The UL1703 STP Module norm requires module manufacturers to list on their module and assembly instructions the specific manufacturer and model numbers of all allowable PV connectors that the module is UL listed to be mated to. This helps installers and inspectors to rely on very clear instructions on what connectors can be used.

The new edition of IEC 61730-1 will require that the connector type which is installed at the module will be printed on the label allowing the installer to know which connector can be used to connect the module.

The installation norm IEC 62548 specifies that plugs and socket connectors mated together in a PV system shall be of the same type from the same manufacturer to make a connection.

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