Yes, Ground mount PV, DC disconnect at array, trench/conduit to house, penetration into basement where inverter is located.
The DCG series? I will look at those, hopefully distributor has better pricing than what I see in google searches.
Why? If the inverter were outside (and they are all designed to tolerate outdoor ambient conditions), rapid shutdown would not be an issue.
For residential, I generally don't install inverters outdoors here in Ohio when the home has a basement or a garage. We get minus 0F temps in winter and 95F temps in summer, and I have replaced enough inverters from competitor's customer systems to reinforce that it is a good decision for this area. Without a disconnect, the DC conductors entering the home become controlled conductors for Rapid shutdown. I also usually install consumption monitoring with all systems and it is not ideal to run CT leads and ethernet to an inverter out in the yard.
Unless you have an interesting local amendment to 690.13 I'm not seeing how having a manual DC disconnect in the circuit changes what is a controlled conductor. How does this work?
Verbiage aside, if you have 'raw' PV DC conductors coming into a building and you put a disconnect on the outside of the building that denenergizes the conductors in and/or on the building, that's a way to satisfy rapid shutdown requirements.
A DC disconnect does not satisfy rapid shutdown requirements for an array on a rooftop; are the rules different for a system like this? On a rooftop, voltages within the array have to get down to 80V within a few seconds. Maybe it's not actually rapid shutdown you are describing?
Yes, a groundmount is different because 690.12 only applies to conductors in or on buildings. So a DC disconnect that de-energizes the DC conductors that are in or on the building can meet rapid shutdown requirements. The rules aren't different, but the situation is.
The dc disconnect becomes the initiator for RSD then if mounted off the building. The location may be an issue since it's up to AHJs which could be touchy if they want it mounted somewhere inconvenient for the installation.
So there is no requirement to drop the voltage between modules in the array?
I'm a bit surprised that 690.12 main paragraph and 690.12(A) aren't a bit clearer on this point. It is certainly possible to read them as saying that if the PV system circuit is "on or in" a building, then rapid shutdown applies to the entire circuit and the array.
I agree that since the array is not on a building, the DC voltages present within a ground mounted PV array do not present a dangerous situation for firefighters, but does the NEC say that?
Yeah, although if the array is a good distance from the house I don't think that meets the spirit of the requirement. But one could put these on the house.
I agree that since the array is not on a building, the DC voltages present within a ground mounted PV array do not present a dangerous situation for firefighters, but does the NEC say that?
What makes sense and what the NEC says are sometimes at odds, in case you haven't noticed.
For the record, I did not read it either way; in fact, I did not read it at all.
It identifies only the circuits installed on or in buildings as requiring RSD. Not the whole PV system, just the circuits on or in a building. If a ground mount system has a circuit that enters a building then only the PV circuits on or in the building are controlled for the purpose of 690.12. Even then you get a 1m allowance so if the circuit penetrates a building and goes right into an inverter with less than a 1m run the DC circuit does not require RSD.
