[RE-wrenches] Sol-Ark 15K AC Output

[William Miller]

Jason:



I am wondering on the advisability of hardwiring the outputs of all four
inverters together.  If one inverter fails the other three can backfeed
into it without any means to disconnect the failed inverter and without
over-current protection.  Have you considered landing the output of each
inverter on a separate, appropriately sized 2 pole breaker in the output
load-center?



In the same vein, how are you feeding generator input into the inverters?
Are these hard-wired paralleled as well?  You might consider having the
generator feed a dedicated load-center with an appropriately sized breaker
to feed each inverter.  You protect the conductors as required and you can
isolate any inverter for service



What size should these breaker be?  If your inverter can supply 62.5 AAC,
upsizing for continuous duty and to the next higher standard breaker size
you get 80 amps.  If you use 80 amp breakers into and out of each Sol-Arc
you require #4 copper at 75°C.  Each inverter and all of the conductors are
protected for the max current they will see and you get the combined
amperage at your output.  There should be no need to run 400 amp wire.



BTW, you can easily contrive a bypass system by creating a sliding
mechanical interlock.  You run an appropriately sized feeder between the
generator fed and inverter fed panels.  The bypass breaker in the
inverter-fed panels is interlocked with the inverter output breakers.  The
installation might look like this
<https://millersolar.com/MillerSolar/Portfolio/Inverters/battery_iinverters/Chimney_Rock/Chimney_rock.html>.
This is way cheaper and easier than installing an additional 200A,
double-throw safety switch.  (A home-made interlock may not be listed but
what is the worse that will happen if all breakers are on?  The inverters
will detect backfeed and shut down.  No harm will come of it.)



Hope this helps.



William



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985





*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Jason Szumlanski via RE-wrenches
*Sent:* Tuesday, March 26, 2024 2:26 PM
*To:* RE-wrenches
*Cc:* Jason Szumlanski
*Subject:* [RE-wrenches] Sol-Ark 15K AC Output



I am going to have a quad-stack of Sol-Ark 15K for an off-grid 120/240V
system with a 150A generator. I know the max real power is 62.5A each
inverter including battery and PV. That would be 62.5A x 4 = 250A total. I
intend to connect the output of the 4 inverters together with a 5-port
Polaris tap, with the output of the Polaris Tap going to a 400A main lug
only panelboard.



My question revolves around the 200A passthrough capability for the
generator, which is 150A max output and would be connected to the Grid
input on each inverter. Since each inverter would need to handle the full
pass-through current, that would require minimum 150A conductors on the
input side of each inverter. I am under the impression that the inverters
can supplement the "grid" or generator in this case if the current exceeds
the available input. That means the inverter would have 150A of input plus
62.5A  of inverter power for a total of 212.5A. But there is a 200A load
OCPD, so I could size the load conductors from each inverter for 200A.



Obviously the 4 inverters can only pass through 150A from the generator in
total, which would probably be split among them, but could go through a
single unit if the rest fail.



Now, is it possible for each inverter to output 62.5A each PLUS 150A of
generator power spread across them for a total of 400A? That is important
because I would need to size the combined output conductors for 400A if
that is the case.



I guess I'm not clear on how Sol-Ark 15K handles grid/generator
assist/supplement. It does not seem to be documented clearly.



Jason Szumlanski

Florida Solar Design Group
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