By: Brian Mills, Product Manager of Photovoltaics for Multi-Contact North America
The practice of claiming one’s PV connector is acceptable for cross-mating to that of another company’s connector has unfortunately become alarmingly common place. For the sake of clarity, “cross-mating” refers to the plugging of two connector halves of a different type or from different manufacturers. Popular products, such as certain manufacturer’s family of connectors, are often a target for companies to claim cross-mating compatibility. However, unless the two connector manufactures enter into a joint certification through the accepted certification agencies (UL, CSA, TUV, etc), the certification for cross-mating to another company’s product is not permitted. The situation of two companies in a joint certification is extremely rare, if not non-existent, for PV connectors. Therefore, any company claiming to have a connector certified for intermating with another’s brand is being dishonest, if not flat out lying.
Since some companies will even display a third-party test lab report from a reputable certification agency and try to pass it off as a certification (these reports often state clearly that they do not constitute a certification), the most assured way to check if a product can be mated to another company’s product is to check the certification agencies websites directly. All the major organizations, such as UL or TUV, maintain an online certification directly that can be searched for what is covered by a company’s certification. Often times, a statement such as “this connector system has only been investigated for use with products within its own product line” can be found.
The persistence of cross-mating connectors is a serious issue, with dire consequences including burnt connections, arcing failures and even structure fires. In the best case, the connectors mate so poorly that no electricity at all will pass through the connection and the system installer will become aware that something is wrong. However, this is not typically the case and the problems instead do not manifest themselves right away. Usually the cross-mated pair of connectors will connect together and pass electricity without any easily noticeable issues. But the misalignment of design dimensions and material compatibilities over time (may take even years) can lead to loss of weather tightness and run away contact resistance that leads to eventual catastrophic connector failure.
The performance requirements for PV components are exceptionally severe: Survive outside in temperatures swinging from below freezing to near boiling, in direct sun or driven snow, arid dry or soaking wet, for 20+ years without failing. A PV connector in a 1,000-V system may easily have as much as 30 kW of DC energy flowing through it, which is more than the service energy supplies to an entire residential home. Therefore, the deceptively simple looking PV connector requires a tremendous level of engineering consideration, testing, validation and quality control to meet these requirements. Trusting that another company has achieved the same level of assuredness when mating to another company’s product without any actual exchange of design or construction information ever taking place between them is extremely dangerous.
Please help maintain the PV industry’s reputation for safety and reliability by spreading the word about the dangers of cross-mating. The safest and most reliable habit is to always mate only connectors from the same manufacturer.