Rapid Shut Down question

[texie]

If you have a rooftop system mixed with string and micro invertors how do you handle rapid shut down? If you had only micro invertors the A/C disco at the tap point would suffice but the string invertors would need shut down modules at the array connected to a pilot device. But doesn't the shut down system have to act as one? If so, can you put a RSD module ahead of a micro invertor?
Full disclosure, I'm not by any means a PV expert understand most of the basics. Help me understand...

 

[ggunn]

If you have a rooftop system mixed with string and micro invertors how do you handle rapid shut down? If you had only micro invertors the A/C disco at the tap point would suffice but the string invertors would need shut down modules at the array connected to a pilot device. But doesn't the shut down system have to act as one? If so, can you put a RSD module ahead of a micro invertor?
Full disclosure, I'm not by any means a PV expert understand most of the basics. Help me understand...

If the string inverter has SunSpec and the modules connected to it have RSD devices, or if it is a SolarEdge inverter, the PV AC disconnect or main service disconnect will serve as the RSD initiator for all the PV.

 

[texie]

Thanks for the help. I will have more questions later when I can have the plan available.

 

[Carultch]

But doesn't the shut down system have to act as one? If so, can you put a RSD module ahead of a micro invertor?

You can have multiple forms of rapid shutdown initiated by the same device (usually an outside-mounted disconnect that doubles for another purpose anyway), if you have a mixture of any combination of microinverters, Solaredge inverters, and conventional string inverters. Usually, just shutting off AC power to the system is your initiation method, as it is either an inverter integrated rapid shutdown medium, or powered as an auxiliary load from an AC combiner.

String inverters don't necessarily have Sunspec rapid shutdown by default. Some do, others may have no integration of rapid shutdown, and would require a separately installed transmitter.

 

[jaggedben]

The rapid shutdown system does not have to act as one. The rapid shutdown intitiation can be up to six switches, similar to a service. So if you have no more than six separate systems they can each have their own rapid shutdown switch. The code does require them to be grouped.

Note also the reference in 690.56 (C)(1) to signage for multiple systems that might have a different type of rapid shutdown or no rapid shutdown. This is a nod to the fact that an AHJ might grandfather an earlier system that doesn't have rapid shutdown along side a newer one that requires it.

 

[texie]

OK, so are you guys saying that one could have a RSD system for the string inverters with, say, a mushroom button, and then the micro section of the rooftop could simply rely on the opening of the PV disco?

 

[jaggedben]

OK, so are you guys saying that one could have a RSD system for the string inverters with, say, a mushroom button, and then the micro section of the rooftop could simply rely on the opening of the PV disco?

Yes. As long as they are all labeled as rapid shutdown switches.

 

[texie]

Yes. As long as they are all labeled as rapid shutdown switches.

Thanks for the help.