The other option is Midnite Solar's remote controlled breakers or
combiner boxes. They make up to a 250 amp breaker, but I found on large
battery systems that we need some thing larger. Colorado is now
requiring Rapid Disconnect for the batteries as well, which is NOT the
original intent of that article. Is the Gigavac UL listed?
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 9/24/2015 10:45 AM, Starlight Solar Power Systems wrote:
William and Wrenches,
I have pondered situations like this one and wonder the following: If
a high voltage DC solenoid were placed at the PV array and the coil
was controlled by an arc fault detector along with a means of manually
disconnecting, would that not work to satisfy shut down requirements
and safety concerns?
We have been using 350A, 800 volt solenoids from Gigavac in our
lithium battery system on both the positive and negative terminals
(controlled by a CPU) to provide 100% disconnect if case of any
battery fault.
Larry
On Sep 23, 2015, at 2:26 PM, William Miller <will...@millersolar.com
<mailto:will...@millersolar.com>> wrote:
Dear Fellow Wrenches
Below is a design conundrum that may resonate with some of you:
We are finalizing a design for an off-grid residential system. The
customer insist the PV should be on the roof and pre-installed a
1-1/4” PVC conduit from his roof to a crawl space, in anticipation of
a solar install. This created real problems, because we all know we
can’t pull PV source or output circuits in (or now, on) the envelopes
of habitable buildings.
There was no practical way to replace the PVC. We contrived a method
to sleeve ¾” liquid-tight through the 1-1/4” PVC to the crawl space,
continuing on with EMT. This is the largest metallic conduit we could
fit. The distance was greater than 10 feet so we couldn’t use EMT.
Due to the conduit size restriction, we upgraded to Morningstar 600
volt charge controllers, allowing us to reduce conductor size.
(As a sidebar, although the Morningstar is listed as a 600 volt charge
controller, we have found no circumstance were we could take advantage
of that high a voltage. With the currently available high wattage
modules, by the time we added enough in series to get to 600 volts, we
were well beyond the wattage capabilities of the controller. For sake
of design considerations, I suggest one regard these units as ~300
volt charge controllers.)
We now have plans for 300 volt PV feeders running down an interior
wall and under the house, with no roof-top disconnecting means. It is
my understanding none are required. I am not comfortable with this.
In this scenario, there is no safe way to replace either of the two
Morningstar controllers. Should someone drill through or damage the
EMT in the wall or under the floor, there would be no way to turn off
the feeder.
I don’t like putting HU361RBs on a roof. They must remain vertical and
so they stick up too high and are hard to provide mounting for.
Sola-deck units are another option, but they require integrating with
shingles, not practical on this job or many others. I finally settled
on a DC-Sunvolt PV-X16A-4X-RG disconnect as a possible solution. At
$216 it is not out of range. The unit will provide means to turn off
the feeders for service. I will report back on my impressions of the
unit.
To distill this scenario, I don’t believe the code requires a
disconnect, but I feel morally obligated to install one. I’d be
interested in verification of the code interpretation and others
response to similar situations.
I found no other options for rooftop disconnecting means that would be
small, reasonably priced and not present a high profile. If there are
products I don’t know about, I would be most grateful to receive your
input.
While researching the hardware I stumbled upon this article, linked
below. It seems to present a real dilemma, but I am not convinced.
Please remain skeptical as you read. It appears all of the links
direct you to the same source.
https://www.linkedin.com/pulse/greatest-debacle-solar-pv-australias-rooftop-dc-isolator-lucas-sadler
Thanks again to all of you for helpful advice and expertise. I
learned about Sunvolt here, just one of many great suggestions.
Sincerely,
William Miller
<image002.jpg>
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600
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