-------- Forwarded Message --------
Subject: Re: [RE-wrenches] Rapid Shutdown and January 1 2019 option?
Date: Fri, 6 Jul 2018 16:37:47 -0600
From: Ray <r...@solarray.com>
To: Rebekah Hren <rebekah.h...@gmail.com>
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 <danbo...@gmail.com
<mailto:danbo...@gmail.com>> 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 <r...@solarray.com
<mailto:r...@solarray.com>> 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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