[RE-wrenches] Combining Multiple Inverters

jay peltz jay at asis.com
Fri Jun 27 06:37:47 PDT 2014


Hi guys,

Sma installation manual us-5000-8000 inverters. 
section 6.5, page 42. 
Maximum over current protection 50 amps. 

Section 6.5.1, page 42
 #6 wire max. 




Jay

Peltz power






> On Jun 27, 2014, at 4:53 AM, Richard.L.Ratico at VALLEY.NET (Richard L Ratico) wrote:
> 
> I may be playing devil's advocate here, but I want to add a few thoughts. Jay, I
> just looked at Fronius and SMA inverter data sheets. I found no spec. for an
> output OCPD, only a spec for max. output current.
> William, most inverters now come with integrated DC/AC discos. Dave, 2014 NEC
> 705.12(D)(1), IMHO, specifies ONE OCPD for the entire interconnected power
> system, not individual OCPD for each inverter.
> 
> Generally speaking OCPD is provided for the circuit conductors in a system, not
> the individual pieces of equipment. If the equipment manu. specifies OCPD, that
> is a different story.
> 
> I understand the 2014 code to require appropiate OCPD for all the conductors
> from the panelboard to the inverter. If that can be accomlished with one device
> at the panel, it meets code. That said, code is a MINIMUM standard.
> 
> Bottom line, I agree with Corey that there is no code requirement for individual
> OCPD for each inverter. If there is, unfortunately, it is insufficiently
> explicit such that we are having this conversation.
> 
> Dick Ratico
> Solarwind Electric
> 
> 
> --- You wrote:
> I have never seen an inverter that does not specify a OCPD size. 
> 
> Jay
> Peltz power. 
> 
> Sent from my iPhone
> 
>> On Jun 26, 2014, at 3:20 PM, Dave Click <daveclick at fsec.ucf.edu> wrote:
>> 
>> Corey,
>> 
>> The line of reasoning is faulty. It's 705.12(D)(1). Micro-inverters are the
> exception because they are specially listed to share a breaker. As for the other
> inverters, doubling them up on a single breaker / disconnect probably goes
> against their installation instructions [110.3(B)] and it's unlikely that you
> could put multiple units on a single breaker anyway because when you take (2
> inverters) x (rated current) x (1.25) you will probably come up with a minimum
> breaker size that is larger than the maximum allowed under the NRTL listing to
> UL 1741.
>> 
>> Dave
>> 
>> 
>> 
>>> On 2014/6/26, 16:18, Corey Shalanski wrote:
>>> We considered the necessity to shut down individual inverters and determined
> that the added costs of an inverter output combiner panel were not merited. I
> agree that in theory it seems beneficial to be able to switch each inverter
> individually, but how often does this occur in practice? For the relatively
> infrequent cases where we need to return to a jobsite and shut down an inverter
> - for troubleshooting/removal/etc. - we do not mind shutting down the other
> inverters (up to a limit) for what is hopefully a short period of time.
>>> 
>>> Again, this whole line of reasoning may be shown to be faulty if someone can
> directly point to the Code section that requires OCPD on each individual
> inverter.
>>> 
>>> --
>>> Corey
>>> $E1eB
>>> 
>>> 
>>>> On Thu, Jun 26, 2014 at 9:20 AM, <re-wrenches-request at lists.re-wrenches.org>
> wrote:
>>>> 
>>>> Message: 5
>>>> Date: Wed, 25 Jun 2014 19:17:57 -0700
>>>> From: William Miller <william at millersolar.com>
>>>> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
>>>> Subject: Re: [RE-wrenches] Combining Multiple Inverters
>>>> Message-ID: <04F4B8FD-E280-4BF2-B5A4-C2FCA8D1C7A6 at millersolar.com>
>>>> Content-Type: text/plain; charset="utf-8"
>>>> 
>>>> Not allowed. You need a dedicated OCPD. Plus seems like a really bad idea. 
> How do you shut down just one inverter?
>>>> 
>>>> 
>>>> 
>>>> Miller Solar
> --- end of quote ---
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