Here is a wild idea. If you look at the Enphase inverter systems,
several inverters connect together in parallel before going to an
overcurrent device.
In all cases, the point of connection to a utility system must be at
a dedicated breaker. If there were multiple string inverters that
would connect to one breaker, why not just use a junction box,
instead of a combiner panel? You could put in an AC disconnect for
each inverter, if it didn't come with one.
The wiring would need to be sized for the combined output of the
multiple inverters, which in many cases wouldn't be an issue.
Drake
At 12:36 AM 1/13/2010, you wrote:
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Andrew,
It does not exist. We tried like crazy to get it into the 2011 NEC,
but to no avail. At the last second the proposal was put on hold
until the 2014 NEC. Major bummer. For now it can only be done with
AHJ approval. Many allow it but it is not in the NEC. Alternatively
you must use the sum of supply breakers no greater than 120%. Much
more restrictive.
Bill.
From: [email protected]
[mailto:[email protected]] On Behalf Of Andrew Truitt
Sent: Tuesday, January 12, 2010 10:57 AM
To: RE-wrenches
Subject: [RE-wrenches] Solar accumulation panel
Team wrenches - I feel like I've seen a provision in the Code for
installing a sub-panel to aggregate PV inverter outputs for the
purpose of simplifying the actual grid connection (such as for a
line-side tap) but I can't find it in 690. I also seem to remember
specific verbiage that needs to be on the panel along the lines of
"PV circuits only. Do not add load breakers." to ensure compliance
with 690.64(B). Does anyone know where I can find this info in the NEC?
Andrew Truitt
Standard Solar Inc.
--
"Don't get me wrong: I love nuclear energy! It's just that I prefer
fusion to fission. And it just so happens that there's an enormous
fusion reactor safely banked a few million miles from us. It
delivers more than we could ever use in just about 8 minutes. And
it's wireless!"
~William McDonough
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648
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