Basically in a nut shell if the PV wires are inside the building more than 5ft they need a way to shut them down
Just curious, our rack mounted grid tie install has no DC disconnect outside at all. It only has the DC disconnect on the Sunny Boy which is mounted on the wall just inside from the buried DC conduit entry. It probably has 6 or 8 feet of actual cable inside conduit but the connection to the inverter is only a couple feet from the conduit entry point.
There is an A.C. disconnect on the outside of the house. Installed last November, no one thought we needed any exterior DC disconnects at all. If they were on a roof mount or otherwise mounted on the house they wanted the rapid disconnect setup? This grid tie system pushes 3X circuits of ~300 VDC to the inverter. Frankly, I wish I had a disconnect at the panels for maintenance as the DC circuits are lethally hot whenever they are illuminated.
I asked the inspector(s) lots of questions, including about disconnects but they were pretty clueless on the exact needs so we did what the solar installer usually did and the inspector was unconcerned with a disconnect but they had never done a grid tie solar setup before.
I guess that falls under "ask your local authority".
So this topic is interesting to me.
Just from here.