What are installers seeing re: 2014 NEC 690.15(C)?

[Amy@altE]

Everyone dealing with solar design where NEC 2014 is enforced is more than aware of the dreaded 690.12 Rapid Shutdown requirement. Microinverters have got that covered, as do optimizers, such as SolarEdge with the Rapid Shutdown kit installed, and the inverter outside (or within 5' of inside). However, I have a question about 690.15(C), which I understand is hotly debated. Direct-Current Combiner Disconnects. The dc output of dc combiners mounted on roofs of dwellings or other buildings shall have a load break disconnecting means located in the combiner or within 1.8 m (6 ft) of the combiner. The disconnecting means shall be permitted to be remotely controlled but shall be manually operable locally when control power is not available.

The way I read this, it is saying that even if you have optimizers, if you are using a combiner box, it has to be a disconnecting combiner box. We've been using them for non-optimizer designs, but do they have to be in all designs now?

I know there are some of you who have been installing SolarEdge for a while, we just started, so I'm trying to find out what you are seeing in the real world. What are AHJs looking for? Is Rapid Shutdown enough, or do you have to also have a disconnecting combiner box? What about pass-thru boxes, do they have to be disconnecting as well? If just going straight through into conduit into the inverter, do you need a disconnect at the array? Any help is greatly appreciated.

[Amy@altE]

I just posted this in Mike Holt's forum as well, but since it's my first post there, I need to wait for a moderator to approve it. I'll post that reply here, assuming I get an answer. But if anyone here has talked to their AHJ about it, I'd love to hear what's being said.

[Amy@altE]

I just got this reply from SolarPro Magazine. So it looks like I was reading that right. If you are using a combiner, it has to have a means of disconnect within 6'. So either a disconnecting combiner box or an external disco nearby. If you are passing through at the roof and combining at the inverter, as long as the system has a Rapid Shutdown solution, you don't have to have a disconnect on the roof. (He said 690.15(D), but I think he meant (C).)

"Looking at the definition of a dc combiner, you should not have to apply 690.15(D) to a pass-through box.

If you look at the evolution of Code requirements over several cycles, the Code-Making Panel is really encouraging installers to locate serviceable parts, like fuses, at ground-level. 690.15(D) is part of this larger trend. It is expensive to put a bulky disconnecting combiner on the roof. If you don't do any combining on the roof, you can use more compact equipment that (hopefully) reduces your costs. After all, many inverters have an inverter-integrated dc combiner."

[Sunking]

Amy go to a Professional Forum and ask that question. Mike Holt Code Forum. Sign up and join, then ask in the PV section. Let me know when you join and I can go approve so you can ask questions.

[Amy@altE]

I did, that's where I got the answer from SolarPro. I just thought some of the regulars here would have seen it out in the field.

[Amy@altE]

I was going to ping you if I didn't get approved quickly, but they were johnny-on-the-spot and got me through right away.

[n9lri]

The new code

If you keep reading you will also find that a disconnect is now required for any combiner installed an if you have more than one each will require a disconnect.

Why because people are pulling fuse holders with power on and causing arcs that burn up combiners.
There has been several instances where someone tipped out a fuse holder and it arcs over inside.
The real goal is to do away with combiners completely.

Fronius also has a rapid shutdown system in the works. Solectra also has a combiner with Rapid shutdown vacuum relay but it's expensive.


We do everything possible to keep away from combiners. There has been far too many roof fires in combiners.
the new rules is clear. You use a combiner there must be a disconnect right after it. This rule change has nothing to do with rapid shutdown.

Were about to shove 80KW on a large senior apartment building and there will not be one single combiner.

[Amy@altE]

Thanks n9lri (and welcome to the forum). The nice thing about SolarEdge is you can do the long strings, so with dual MPPT, there's not a lot of times when a combiner is needed. This just took me by surprise, I had seen so much about Rapid Shutdown, this one slipped under the radar. Most of the time, pass thrus will do the trick, especially since more inverters are doing the dual MPPT, but I'm also thinking about odd cases where a combiner is needed.