Zane Bailey
Member
Lately I have been asked to inspect a lot of Utility interactive Inverters for both Solar and Battery storage. In both cases the inverters are labeled with the Utility Interactive rating label (NEC requirement) and also have the UL 1741 labeling.
The inverters are listed and labeled with a DC short circuit rating; however, they have no labels that indicate an AC short circuit rating.
All of the projects have had Short Circuit Coordination Studies (SCCS) performed. The studies show that the AC available fault current at the inverter locations are roughly between 6195 ka to say 8100 ka phase to ground fault. The manufactures cannot provide any information that would determine that the inverters were tested to withstand fault current at these levels.
I find it hard to believe that a piece of equipment that interacts with the Utility grid and Is permissible by Code to be connected line side of the service equipment (upstream of main breaker), would not have a AC SC rating let alone a very high rating.
I am being asked to allow this equipment to be energized without this verification being made.
Has anyone else in countered this or can shed light into this?
Zane.
The inverters are listed and labeled with a DC short circuit rating; however, they have no labels that indicate an AC short circuit rating.
All of the projects have had Short Circuit Coordination Studies (SCCS) performed. The studies show that the AC available fault current at the inverter locations are roughly between 6195 ka to say 8100 ka phase to ground fault. The manufactures cannot provide any information that would determine that the inverters were tested to withstand fault current at these levels.
I find it hard to believe that a piece of equipment that interacts with the Utility grid and Is permissible by Code to be connected line side of the service equipment (upstream of main breaker), would not have a AC SC rating let alone a very high rating.
I am being asked to allow this equipment to be energized without this verification being made.
Has anyone else in countered this or can shed light into this?
Zane.