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

Wed Mar 27 03:12:15 PDT 2024

William,

Thanks for the information on grid peak shaving. That is what I thought
could be done. The description is a misnomer of sorts (like a lot of things
in Sol-Ark lingo). It's a bit hard to follow and not nearly well
enough documented, particularly with respect to parallel systems.

I follow what you are saying about using the 80A input breakers. The
problem I have is that you must set the generator kW to 36,000 in the
master inverter, not 9,000W in each inverter. The concept of "underrating"
the input breakers theorizes that each inverter will share the generator
pass-through equally. I do not know that to be the case. And what happens
if the three slave inverters have a fault or are turned off? That would
allow the single master to pass through the full generator supply.
Obviously this trips the 80A input breaker and protects the conductors, but
I feel that is a design deficiency when a single inverter is fully capable
of passing through all 150A.

On top of that, I don't think the 80A output breakers are sufficient
because each inverter can peak shave 50A with inverter power from the
batteries. Add that to the theorized balanced 37.5A "grid" input, and you
are at 87.5A of possible throughput.

But assuming the 80A input/output concept works, other than a panelboard
with bolt on breakers, what low-cost load center allows you to fasten four
80A backfed breakers? If this is available, I could use a recommendation.
The load centers I am familiar with only have provisions for one fastened
backfed breaker.

With respect to the bypass, I would usually use a DPDT switch to accomplish
this, Even for 400A bypasses, there seems to be a relatively cost effective
option in the Ronk 7416 (which to date I have not used). I get the concept
for smaller (<=100A) generators that you could use a generator interlock on
an off-the-shelf load center. But they typically only allow a single
backfed 2-pole breaker, whereas something like a Square D QO panel with a
backfed 150A breaker requires 4 spaces and is incompatible with the
interlock device.

Always, this is a great discussion and specific recommended equipment is
appreciated.

Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208

On Wed, Mar 27, 2024 at 12:33 AM William Miller <william at millersolar.com>
wrote:

> Jason:
>
>
>
> Sol-Arc does provide generator support.  They call it “grid peak load
> shaving” and it is described on page 22 of the manual.  Below is an excerpt.
>
>
>
>
>
> For those that may not be familiar with the concept of generator support,
> here is how I describe it:  The inverter(s) are programmed for the
> generator capacity.  If the generator is powering loads and the demand
> exceeds that programmed generator capacity, the inverter can start
> inverting and synchronize output to the generator to add power.  This is
> only possible if battery charge levels are adequate.  In the Sol-Arc this
> function can be adjusted or turned off.
>
>
>
> Regarding my recommendations on wire sizing:  I may have done a poor job
> describing how I see your project best approached.  Below is a diagram that
> may do a better job.  Power flow is from left to right:
>
>
>
>
>
> If you follow what I am laying down, you can see there is no single
> inverter or inverter wire that can pass or create more than 80 amps.  Ergo
> #4 copper.  The money and time you save can easily purchase 8 80 amp
> breakers.  If you look at Diagram 10 in the April 5, 2022 Sol-Arc manual
> you will see this concept shown, albeit without bypass capabilities and
> with a separate “LOAD AC Combiner panel.”  The separate panel is
> redundant,-- all of the breakers in the AC combiner panel could be located
> in the “Main Breaker Panel.”
>
>
>
> Contemplate this:  Just because an inverter can pass-through 200 amps,
> does not mean it can pass through amps above what the input breaker
> provides.
>
>
>
> I hope I have been more clear.  I also hope you don’t spend a lot of money
> on and wrassle wire larger than is needed.
>
>
>
> Call me if I can help in any way.
>
>
>
> William
>
>
>
> PS:  Below is a diagram on how to provide bypass.  I tried to depict the
> bypass interlock graphically.  The point is you cannot turn *on* the
> bypass breaker without turning *off* the inverter output breakers.  See
> photos of the actual hardware on the web page linked below.  I find bypass
> very handy because if there is an inverter or battery failure the client
> can restore power immediately and I can respond at a more convenient time.
>
>
>
>
>
>
>
>
>
> Wm
>
>
>
> Miller Solar
>
> 17395 Oak Road, Atascadero, CA 93422
>
> 805-438-5600
>
> www.millersolar.com
> <https://mailtrack.io/l/3deb3f7f51095bae3cfd8b42df221b4dca044e0a?url=http%3A%2F%2Fwww.millersolar.com%2F&u=1613865&signature=79e9e2e0e8d662d0>
>
> CA Lic. 773985
>
>
>
>
>
> *From:* Jason Szumlanski [mailto:jason at floridasolardesigngroup.com]
> *Sent:* Tuesday, March 26, 2024 6:41 PM
> *To:* William Miller; RE-wrenches
> *Subject:* Re: [RE-wrenches] Sol-Ark 15K AC Output
>
>
>
> #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://mailtrack.io/l/e90ccdb6d87171ee02747bc52f4aa4c7f57064ca?url=https%3A%2F%2Fmillersolar.com%2FMillerSolar%2FPortfolio%2FInverters%2Fbattery_iinverters%2FChimney_Rock%2FChimney_rock.html&u=1613865&signature=38c4488f52bdc385>.
> 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
> <https://mailtrack.io/l/7e13e4b3b56e5496552a9f21904f404635490f63?url=http%3A%2F%2Fwww.millersolar.com%2F&u=1613865&signature=6c634bcc39faeca3>
>
> 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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