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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