PV Connectors: Task Group 10
Task Group 10 focuses on durability issues related to photovoltaic (PV) junction-box connectors, including both manufacturing and deployment issues. It will examine evidence for and initiate tests on durability and reliability of contacts, and susceptibility to mechanical or corrosive failure mechanisms.
Plastic wall materials need to retain their strength against ultraviolet (UV) exposure. The connectors should keep the joints rigid and interior sealed to humidity and dust, and protect the connector joints against reasonable external mechanical forces during installation and use. Standards and procedures are needed at the times of manufacture, installation, and for field repair/retrofit of connectors.
Task Group 10 has conducted a survey to prioritize efforts, reviewed standards already in place for their applicability to durability studies and is now working through a design failure mode and effect analysis to identify the most critical failure mechanisms.
Field failures are being sent to Mike Kempe at the National Renewable Energy Laboratory (NREL) for failure analysis. His lab is able to complete a computer-aided X-ray tomography scan (computerized tomography [CT] scan) of these samples. The CT scan provides high-quality images of a failed connector that help determine the root cause of the failure. If samples continue to show similar failure modes, the team will need to ensure there are standardized tests to address the issue. The International PV Quality Assurance Task Force is asking industry to submit field failures of PV connectors/cable to NREL for further analysis.
Interconnectability of unlike PV connectors has been a reoccurring topic within this task group. Its ultimate goal is to standardize the enclosure of PV connectors (i.e., National Electrical Manufacturers Association to ensure there are no safety hazards that may occur when mating unlike connectors or mating connectors that have not been tested together. This is a long-term solution that will need industry leader support to help implement. In the interim, the task group is trying to spread the word that mating of unlike connectors can be a safety hazard and lead to field failures.
Task Group 10 has reviewed and commented on the IEC TS 63126 ED1 proposal from Kent Whitfield (NEXTracker). There is still some ongoing discussion regarding the requirements for UV exposure, but the temperature limits have been addressed and have been submitted to the committee for review.
The task group has started to identify discrepancies between UL 6703 and IEC 62852. For example, there is a discrepancy for voltage limits (1000 Vdc versus 1500 Vdc) between the standards for single pole versus double pole.
This is very recent, so not much time has been spent on this task. This will be reviewed going forward.
PV Connector Voltage Ratings on Different Standards
|UL6703 Ed.1||UL6703 CRD 150629||C22.2 No. 182.5-14||IEC 62852:2014|
A proposal concerning UL 6703 has recently been sent out that would require all connectors to be shipped with caps to prevent corrosion. It appears there is not enough data to support it. If anything, this should be a recommendation and not a requirement.
- Is there a cleaning procedure published by the connector manufacturers to clean heavily soiled connectors? The task group will need the connector manufacturers’ input on this.
- Is there a test (i.e., contact resistance) that can be done to see if connectors coated with Arizona dust will cause failures in the field?
Bryan Skarbek — First Solar, representing the Americas
Alan Xu — Canadian Solar, representing China
Yingnan Chen — China General Certification Center
Other leaders are welcome.