JASON:
The reference temperature for the Square-D breakers is 40C/104F, as
opposed to 20C/68F for the ABB breakers. The possibility of a "nuisance
trip" due to derating would occur sooner for a 20A ABB breaker than for
a 20A QO/QOB breaker.
I received a follow-up e-mail earlier today from Steve Capozzi of SolaDeck:
-------- Original Message --------
Subject: RE: SolaDeck
Date: Tue, 27 Nov 2012 07:20:17 -0600
From: Steve Capozzi <scapo...@rstcenterprises.com>
Organization: RSTC Enterprises
To: <g...@icarus-engineering.com>
Gary,
I sent ABB engineering an e-mail yesterday to see if they have any
new items with higher ambient temps.
The breakers we have were the highest at the time we started into AC
systems.
We have never had a issue in the field with these breakers.
I will keep you posted.
steve
Steve Capozzi
President
RSTC Enterprises Inc
2214 Heimstead Road
Eau Claire, Wi 54703
866-367-7782
715-830-9997
I'll keep you posted with what I find out.
Regards,
Gary Willett, PE
Icarus Engineering LLC
Icarus Solar Services LLC
On 11/27/2012 8:30 AM, Jason Szumlanski wrote:
We're pretty fortunate that a roof mounted readily accessible
disconnect has not been a sticking point locally. I would argue that
the AC disconnect is still the trunk cable connector, which can be not
readily accessible. The AC breaker carrying the combined circuit
output in the main distribution panel or the fusible disconnect switch
if performing a supply side connection would qualify as the readily
accessible disconnect. If you install Enphase I'm sure you are
familiar with the manufacturer's excellent white paper on this issue.
I hear what you are saying about the temperature concerns, but there
are many installations that have far fewer than 17 inverters per
string. A typical residential installation can be split into two or
three branch circuits (thank you, Andrew, for keeping me accurate on
the string/circuit thing!) The temp concern is definitely something to
explore further. There is also the thermal interference factor to take
into account for multiple breakers that Gary did not mention. The full
datasheet is here:
http://www05.abb.com/global/scot/scot209.nsf/veritydisplay/11d7d0032b466358c125712400340107/$file/2CDC002052D0203_UL489.pdf
As for the "interior rated" breaker comment, typical AC branch circuit
breakers (i.e. Sq D QO) are mounted in wet location NEMA 3R boxes all
the time on the exterior of a building. I'm not sure I understand this
concern. The temperature derating curve is also similar for ABB and QO
breakers. QO Datasheet here:
http://static.schneider-electric.us/docs/Circuit%20Protection/Miniature%20Circuit%20Breakers/QO-QOB%20Circuit%20Breakers/0730CT9801R108.pdf
I definitely want to be 100% sure the SolaDeck and breakers are
appropriately rated before proceeding. Any comments welcomed...
*Jason Szumlanski*//
/Fafco Solar/
On Mon, Nov 26, 2012 at 6:37 PM, Gary Willett
<g...@icarussolarservices.com <mailto:g...@icarussolarservices.com>>
wrote:
JASON:
I talked to Steve Capozzi of SolaDeck and he sent me additional
info about the circuit breakers:
_Manufacturer_: ABB
_Terminal Temp Rating_: 75C / 167F
_Reference Temperature_: 20C / 68F
_Ambient Temp Derating_:
30C/86F = 18.7A
40C/104F = 17.3A
50C/122F = 15.8A
60C/140F = 14.1A
70C/158F = 12.2A
My concern is that we may be attempting to use an interior rated
AC breaker in a roof-deck-mounted NEMA3-R enclosure.
In an Enphase application, with the maximum of 17 inverters per AC
Source Circuit, the continuous current will be 0.9A x 17 x 1.25 =
19.1A. This exceeds the 30C/86F trip current of 18.7A.
The interior temperature of the SolaDeck could very likely
approach the 60C/140F trip current of 14.1A.
It seems to me that "nuisance trips" could be a high probability
event.
Does anyone have any field experience using this Soladeck option
for a AC Source Circuit Combiner Box (SCCB)?
Another issue, at least in some jurisdictions, is the requirement
for a roof-top AC Disconnect.
The SolaDeck, when used as an AC SCCB, may not meet the NEC
Article 100 requirements in some jurisdictions for "readily
accessible" because a tool is required to open it.
Regards,
Gary Willett, PE
Icarus Engineering LLC
Icarus Solar Services LLC
On 11/26/2012 2:21 PM, Jason Szumlanski wrote:
I did get some pictures and info from Soladeck. Here are some links:
Pics:
https://docs.google.com/open?id=1BpiL-1SdSNNsj4wPMQrFCLHH7JT2dek_KftSJl06QLqc0yhJ_1t5oij0aEA6
https://docs.google.com/open?id=1cVuhZGeQNHL1IvGvNBa7v93oZyGBvjxCv5yq4AmoyJeDAITxvgMqgECR2yTv
https://docs.google.com/open?id=1umslTplnFyZG1eNCZE-MMi_OqrSeirFCPRBl9mFNZJ2gQkBjM5LEXnaPKy2l
Specs:
https://docs.google.com/open?id=13KLAuxUHOR9al7-36reDSJJ7IMnqV3ANPnJILPnrj2xcAi0ksRj67ifKIe7R
https://docs.google.com/open?id=1kvPFcDc1vruS3W_aONlXyIHm1T8-qi4vTpTwGGJ7H0eIwuZ-5e6zrM1CcND5
https://docs.google.com/open?id=1lM8FtYl9HiYohru32UA_Gb1tXZKZ5iw-8tnSu1Un6g4vcklLL-DK1qLPMdsB
I was told Soligent can source the combiners for you (and me).
*Jason Szumlanski*//
/Fafco
Solar/<http://www.wisestamp.com/apps/wordpress?utm_source=extension&utm_medium=email&utm_term=wordpress&utm_campaign=apps>
On Mon, Nov 26, 2012 at 1:50 PM, Jason Szumlanski
<ja...@fafcosolar.com <mailto:ja...@fafcosolar.com>> wrote:
I just called Soladeck and they are sending me some more info
on availability. I'll pass it along when I get it. I didn't
realize they made an AC roof mounted string combiner
solution. That's a huge help for 2 or 3 string Enphase
installations (they make both combiners).
While on the subject, we recently started using the Enphase
cable couple with Type TC-ER cable to extend cabling to
junction boxes when necessary... No more wasting trunk cable
connectors! I suppose Type TC-ER could be used all the way to
the main distribution panel, thereby eliminating junctions on
the roof, but I haven't looked into the cost/benefit of that
idea.
*Jason Szumlanski*
/Fafco Solar/
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