Thanks Rebekah, At this time, I feel like we are stranded on one option
that used to be very popular with my customers. Unlike most of the
mainland, 95% of our customers want batteries. Right now, we are only
going to do ground mounted dc coupled until we have a chance to evaluate
the Outback system. The combiner box is large and that doesn't excite
some people. Chris
On 7/6/2018 8:23 PM, Rebekah Hren wrote:
Hi Ray and Dan and Chris, etc,
I agree with a lot of what you are saying, don't get me wrong...I have
an off-grid house too and I've been worrying about how module level
shutdown will be implemented and what it means for reliability and
cost, especially dc-coupled battery-based systems that really don't
have or need MLPE.
I'm working on article for the Sept/Oct Homepower about rapid shutdown
and one the things I've been excited to learn about is the new Sunspec
alliance power line communication protocol
<https://www.solarpowerworldonline.com/2017/10/communicating-get-job-done-inverters-sunspecs-rapid-shutdown-standard/>
for receivers and transmitters for RS. As Ray mentioned Midnite is
already selling their SOB
<http://www.midnitesolar.com/productPhoto.php?product_ID=671&productCatName=Software&productCat_ID=44&sortOrder=1&act=p>
(er, haha). And Tigo just got their cheapest RS MLPE option the TSF-F
UL <https://www.tigoenergy.com/library/view/TS4-F+-+Fire+Safety.pdf/>
listed. What's cool is the devices are inverter-agnostic, and don't
need another conductor for data or power running to them. But as Ray
also said, they aren't working with charge controllers, yet.
So I do think there is some good news on the horizon! From the way the
2020 NEC first draft is written, I don't perceive any chance of the
690.12 rules really changing drastically. But something else that may
change the products we can use to meet the requirements is a new UL
standard that is being worked on- UL 3741 PV Hazard control. I don't
know much about it, but here is a list of the people
<https://csds.ul.com/Include/ViewRoster.aspx?GroupID=1782&stpNumber=3741> who
are on the Standards Technical Panel. I think a few of them are on
this listserv so maybe one of them will give us an update!
Best,
Rebekah
On Fri, Jul 6, 2018 at 4:39 PM Ray <[email protected]
<mailto:[email protected]>> wrote:
-------- Forwarded Message --------
Subject: Re: [RE-wrenches] Rapid Shutdown and January 1 2019 option?
Date: Fri, 6 Jul 2018 16:37:47 -0600
From: Ray <[email protected]> <mailto:[email protected]>
To: Rebekah Hren <[email protected]>
<mailto:[email protected]>
Hi Rebekah;
I very much appreciated your previous posts on this. Yes, we do
not need to disconnect the inverter and battery per previous
interpretations. However, the RS system can and will trip for a
variety of reasons, which disconnects the charging system. It
might take a couple of days to discharge the batteries, but the
results are the same: rotten meat in the fridge and a dead
battery. If no one is home, thousands of dollars of battery could
be ruined in a matter of weeks, if its Gel or AGM.
If we get to a point where all the modules have shut down built
in, and the Controllers also have built in disconnect so their
capacitors don't back feed, then it won't be so hard to comply
with 690.12. In the mean time though, off grid should be given a
clear exemption based on array size and Voc of the array. We are
often only wiring 2 modules in series, so we are already well
below 100 v. Rules designed for 600 v arrays should not
unilaterally apply to everyone, just as 600 VAC rules don't all
apply to 120 vac residential. There are numerous exemptions for
lower voltage AC situations, we are just asking that the same
thinking be applied to PV.
Ray Walters
Remote Solar
303 505-8760
On 7/6/18 2:57 PM, Rebekah Hren wrote:
I believe there was a big improvement for off-grid systems as
relates to RS in the 2017 NEC - the diagrams in 690.1(b) all show
the PV system disconnect clearly now. If you check out the
diagrams you can see that energy storage/battery circuits,
including the battery-based inverter whether AC or DC coupled,
are outside the PV system boundary, thus not PV system circuits,
thus not subject to RS.
Also, the NEC 2020 1st draft report has been published
<https://downloads.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=70&tab=nextedition>,
so get your comments submitted!
Rebekah Hren
Member, NEC CMP-4
On Fri, Jul 6, 2018 at 2:22 PM Dan Fink <[email protected]
<mailto:[email protected]>> wrote:
I agree with you, Ray, as a purely off-grid solar installer
and troubleshooter. I think all that was accomplished in NEC
2017 on this issue is that non-habitable structures, like the
common off-grid 'power shed' don't need 690.12 RS anymore.
Dan Fink
Professor of Solar Energy Technology, Ecotech Institute
IREC Certified Instructor™ for:
~ PV Installation Professional
~ Small Wind Installer
Executive Director, Buckville Energy
NABCEP Registered Continuing Education Providers™
NABCEP Associate
970.672.4342
On Fri, Jul 6, 2018 at 11:32 AM, Ray <[email protected]
<mailto:[email protected]>> wrote:
Midnite has some string level and module level 690.12
disconnects that wire in like an optimizer or micro
inverter, so those should be able to meet the 2019
requirements. However beware: they as of yet still
don't have a reasonable disconnect system to disconnect
the charge controller which has capacitors that back feed
the PV line for up to 90 seconds. They have a DC GFI
breaker with remote trip capability but it takes 4
spaces, so with multiple charge controllers it turns into
a wiring mess really fast.
I actually wired in some 60 amp rated diodes on one
system to get it to pass inspection; what a joke, going
back to 1980s equipment to pass 2017 code. 690.12 is an
absolute nightmare for small off grid. There really
should be some exemptions for small arrays (under 3 kW)
and under 100 vdc. Fire fighters are not going to get
there till the structure is down anyway, Response times
are up to an hour for remote locations with volunteer
fire departments. Its not like in town at all; no one
is going to go on the roof on an off grid fire.
On the flip side, there are real dangers created by
nuisance tripping of 690.12 equipment. Again, on grid
it's a mere inconvenience, but off grid it could mean
spoiled food, frozen water lines, shut down heating
systems in subzero temperatures, and for the elderly:
loss of their breathing machines. I've already had a 74
year old customer climbing on their roof multiple times
to reset the Rapid shutdown equipment after nuisance
trips. Are we going to wait until we get someone killed
in the name of "Safety" before we fix this?
Ray Walters
Remote Solar
303 505-8760
On 7/6/18 9:55 AM, cwarfel wrote:
I am wondering about the experience installers have with
a DC coupled multimode system design that will comply
after January 1 with what I feel is the biggest
mistake/poorly guided part of NEC 2017 690, and that is
690.12. We are installing two Outback systems with the
remote controlled combiner and even that won't comply
after January 1 unless we parallel more subarrays
(There's safety for you, lower voltage-higher
amperage!). Thanks for any insight.
Chris
--
Christopher Warfel, PE
ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
(401)466-8978
EEI logo <http://entech-engineering.com>
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