Hi Jason, I talked through this scenario with Sol-Ark tech support a while back. The take away was that grid peak shaving does exist but ONLY on the grid port. If this is an off-grid installation, then land the conductors from the generator on the grid port and select “gen connected to grid port” option.
But in a grid-tied scenario, where the generator is connected to the Gen port, do not expect a smaller generator to get peak shaving support from the inverter, and expect it to overload if an overload is present. Sol-Ark suggested that you could use a ATS to allow the generator and grid conductores to be shared on the single grid port…but that just seems like a clunky idea. On Wed, Mar 27, 2024 at 6:13 AM Jason Szumlanski via RE-wrenches < re-wrenches@lists.re-wrenches.org> wrote: > 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 <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. >> >> >> >> >> >> 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: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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