www.interlockkit.com - they stock and custom make interlock bypasses including multiple breakers.
Square D also makes a 400 A panel which excepts either bolt on or snap on QO breakers. *Kirk Herander / **kirkh@vermont.solar <kirkh@vermont.solar>* *Owner|Principal, VT Solar, LLC* *Celebrating our 33st Anniversary 1991-2024!!* dba Vermont Solar Engineering 802.559.1225 On Wed, Mar 27, 2024 at 3:15 PM William Miller via RE-wrenches < re-wrenches@lists.re-wrenches.org> wrote: > Jason: > > > > Replies below. > > > > Miller Solar > > 17395 Oak Road, Atascadero, CA 93422 > > 805-438-5600 > > www.millersolar.com > > CA Lic. 773985 > > > > > > *From:* Jason Szumlanski [mailto:ja...@floridasolardesigngroup.com] > *Sent:* Wednesday, March 27, 2024 3:12 AM > *To:* will...@millersolar.com > *Cc:* RE-wrenches > *Subject:* Re: [RE-wrenches] Sol-Ark 15K AC Output > > > > 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. You > are welcome. The Sol-Arc manual is not a great manual in any regards. > > > > 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. You may be designing for an eventuality > that will never occur: If the inverters fail then they should be repaired > or replaced. While awaiting repair the bypass will keep your loads powered > at full capacity. > > > > 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. I am not sure why you are designing > to deliver more than the inverters will produce. The generator support > function is intended to assist powering loads when the generator is > undersized. I define that as the generator ampacity being less than that > of the inverter system. The 36kVA generator is greater in ampacity than 4 > Sol-Arc 15s. You can turn the generator support function down or off in > the Sol-Arc. I would recommend it be set to off for this project. (If > there are to be occasional loads that are greater than the inverters can > deliver, like a welder or a car charger, with the plan I suggested you have > a generator-fed panel that can feed those occasional large loads with the > generator running.) > > > > 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. I use to specify bolt-on panels for this but I came to > believe this is overkill. QO breakers are held in place by the panel cover > that overlaps the breakers. Other breakers are configured so the contact > points for the breaker bus are recessed. You need to convince your AHJ > that this satisfies the requirement. Part of the discussion should include > the point that off-grid systems are specialized and people that do not > understand them should not be working on them (or judging them-- is what I > tell inexperienced plan-checkers). > > > > 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. Since bypass is an emergency > condition, I sometimes limit my bypass to 100 amps. If you want full > bypass ampacity you can build an interlock to accommodate any size > breaker. Here > <https://millersolar.com/MillerSolar/Portfolio/Commercial/RM/Interlock.JPG> > is a photo of a large frame breaker being interlocked. Here > <https://millersolar.com/MillerSolar/Portfolio/Commercial/RM/RM_Interlock.pdf> > is a design sketch exploring multiple interlock options. > > > > 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 <will...@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. > > > > *Error! Filename not specified.* > > > > 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: > > > > *Error! Filename not specified.* > > > > 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. > > > > > > *Error! Filename not specified.* > > > > > > 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:ja...@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@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-boun...@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 > > > > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > <https://mailtrack.io/l/5f5ecb45fa0ccb0d11cccafb2c0f97618fa79e70?url=http%3A%2F%2Fre-wrenches.org&u=1613865&signature=fdeabe6cf92ab25a> > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > <https://mailtrack.io/l/020c93287659704ad1c52093f304e341f5d0498c?url=http%3A%2F%2Flists.re-wrenches.org%2Foptions.cgi%2Fre-wrenches-re-wrenches.org&u=1613865&signature=3efe2a50c80c33a7> > > There are two list archives for searching. 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