[RE-wrenches] Combining Multiple Inverters

[Glenn Burt]

How about 705.20 and 21?

 

 

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Corey Shalanski
Sent: Thursday, June 26, 2014 6:11 PM
To: re-wrenches at lists.re-wrenches.org
Subject: Re: [RE-wrenches] Combining Multiple Inverters

 

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Perhaps I should've been more specific with my scenario. I was imagining a supply side connection, as this would more commonly be the case when combining multiple inverters. In this case it seems like the provisions of 705.12(D) for load side conections don't even apply, no? Rather 705.12(A) becomes the relevant section, and I see very few restrictions there.

 

Even with a load side connection I would tend to agree with Jason's interpretation: Does the "source interconnection" in 705.12(D)(1) refer to each individual inverter, or can it refer to an aggregated "source"?

 

I am interested in pursuing this idea, mainly to understand how/where the NEC forbids it. In lieu of a clear Code reference against it, how is this any different from a branch circuit (in reverse)? ie, as with microinverters.

 

--

Corey Shalanski

Joule Energy

New Orleans, LA

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On Thu, Jun 26, 2014 at 9:20 AM, <re-wrenches-request at lists.re-wrenches.org> wrote:


Message: 11
Date: Thu, 26 Jun 2014 09:10:07 -0400
From: Jason Szumlanski <jason at fafcosolar.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Subject: Re: [RE-wrenches] Combining Multiple Inverters
Message-ID:
        <CAJJtG3oQGBLzatinUHFp_GhivzYD6dLdsLAnkc1ofG9tR1RFgA at mail.gmail.com>
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705.12(D) reads, "... the interconnection provisions for the
utility-interactive inverter(s) shall comply with (D)(1) through (D)(7)."
That's inverters - plural. The interconnection must be protected by
dedicated OCPD, not each inverter individually. Microinverters comply
because of this interpretation.

That said, I've never done it. An accumulator panel is pretty cost
effective when you consider the alternative cost of an enclosure and the
Polaris connectors. I guess if you are making the Polaris connections
inside the main load center or inside an inverter you can eliminate the
cost of a dedicated enclosure. There would be some material and labor
savings.

?If the inverter has a maximum OCPD rating, you will be limited by that.
?Microinverters "get around" that by the wire and inverter being
sized/rated for the entire maximum string.

Jason Szumlanski

?Fafco Solar?

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