Yes, microinverters and now I would think other typologies will be
included with module level disconnects becoming more common and I guess
required. So, as long as you can disconnect each non microinverter
individually, and microinverter strings by one disconnect, you should
meeting the intent. Labeling is key too. I still think that this was a
big error and the stated intention of making rooftop pv safer has not
been achieved. The wheel fell off of this "safety improvement".
Technology is catching up though. Anyone on a roof better assume the
array is live until proven otherwise no matter what installation type it
is. Chris
On 2/25/2019 5:45 PM, Rebekah Hren wrote:
I should follow up to say that yes Chris is correct - each inverter
does require its own equipment disconnects (AC and DC) per 690.15, but
those can be connectors, like for Enphase, or any number of other
things, as detailed in 690.15. If you try to keep system and equipment
disconnect rules separate in your mind, I think it helps - although of
course the inverter AC disconnect for a string inverter will often
also be serving as the system disconnect, so there is a lot of overlap.
On Mon, Feb 25, 2019 at 5:39 PM Rebekah Hren <rebekah.h...@gmail.com
<mailto:rebekah.h...@gmail.com>> wrote:
Hi Chris and William
There was certainly no intention to mandate that all inverters
connect to one OCPD/disconnect.But 705.12(B)(1) in 2017 clarifies
that systems like Enphase could have multiple inverters on one
breaker, certainly not that all inverters in a building have to
be on breaker.
If an AHJ raises this issue the answer is as follows:
A single inverter can be called a single PV system - see the
diagrams in 690.1(b). A building can have multiple PV systems per
690.4(D).
Each PV system can have no more than 6 system disconnect switches
per 690.13(D). Circuit breakers are allowed as PV system
disconnects - 690.13(F)(1).
There is no limit to the number of PV systems allowed on a building.
Therefore, each inverter can be connected to its own breaker/disco
for that PV system.
A few further comments :
A single PV system can have a single inverter, or multiple
inverters. It is up to you to define the system and the PV system
disconnect(s) associated with it.
OR multiple inverters (power sources) can be connected to a single
OCPD/disco up to the manufacturer's maximum OCPD limit, per
705.12(B)(1).
OR multiple (let's say 10) inverters in a single system can each
have their own OCPD/disco and ONE master PV system disconnect for
all 10 inverters to follow the fules of 690.13(D).
Lots of options, all allowed!
Best,
Rebekah
Principal, CMP-4
On Mon, Feb 25, 2019 at 5:31 PM Christopher Warfel
<cwar...@entech-engineering.com
<mailto:cwar...@entech-engineering.com>> wrote:
Just reading more slowly, each inverter has to be on its on
separate disconnect means. You cannot put multiple inverters
on the same disconnecting means unless there are individual
disconnecting means upstream.
On 2/25/2019 10:53 AM, William Miller wrote:
Friends:
I have an NEC code question on an upcoming project. It is a
home that has an existing 8 kW ground-mounted grid-tied
system. The owner wants to add another 10 kW of grid-tied
PV. My question is about 705.12, point of connection.
Specifically section (D)(1). That section states:
/The source interconnection of one or more inverters
installed in one system shall be made at a dedicated circuit
breaker or fusible disconnecting means./
So if there are going to be two inverters on premise, do the
outputs have to be aggregated to connect via one circuit
breaker? This might be difficult to do as the exiting
inverter is connected via a different sub-panel than the one
that is planned to receive the new inverter output.
This article
<https://iaeimagazine.org/magazine/2014/01/16/load-side-pv-connections/>
addresses the question.
I would be very grateful if any of you can share any
experience you might have in interpreting this section of the
code.
Thanks in advance.
William
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