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

Tue Mar 26 18:41:08 PDT 2024

#4 wire as the output of each inverter is definitely not adequate, as each
inverter can pass through 150A of generator power. In theory it would be
spit across all four, but that doesn't matter. It's an open spigot, so at a
minimum the output conductors would need to be 150A rated in my opinion.
The complication arises when you don't know whether the inverter can
supplement this AC output all the way to the 200A load OCPD integral to the
inverter. For that reason, I believe you need to size the output conductors
to 200A, not 150A in this case. I am trying to find out definitively if
generator support mode is supplied by Sol-Ark s.

As for paralleling the outputs, landing the outputs on breakers becomes
problematic and very expensive. Since the outputs need to be 150A minimum
or 200A maximum (as discussed previously), how would you do a 400A
panelboard with four of these large breakers in it, keeping in mind that
all four need to be fastened as backfed main breakers? I don't see a
practical way to make that happen.

The same thing applies to combining the generator inputs. You would need 4
x 150A backfed breakers, all fastened to the bus. Is there a cost effective
way to accomplish this?

Serviceability and bypass are obvious desires, but at what cost? If an
inverter needs to be taken out of service, it's fairly easy to remove the
supply and load conductors. And this highlights my issue... What if three
of four inverters need to be removed from service? Then absolute 150A
generator power can flow through the remaining single inverter, meaning the
output conductors need to be sized accordingly.

Jason

On Tue, Mar 26, 2024, 9:15 PM William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> 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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