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I have two multiplus inverters in a mobile set up in split phase that I would like to have match the power input and allow passthrough and assist. There are times when power supplied is from a single phase power source. I do not need 240 volt capabilities. Is it possible for the inverters to see the single phase and fully operate.
I think they can be configured as " do not switch as a group" then you may be able to use one of them with the supply.
you will need to use ve bus system configurator.
I do have them configured in split phase but functionality it not complete. When the inverters test the line voltage and see that the voltage of both L1 and L2 are on the same sine wave, the follower will not allow pass through current or allow the inverte to charge the bank. It will invert full time. I would like the inverters to just match the wave of the input power supplied.
Hi, thats not possible. You have to set the type during configuration, they will not auto-adapt.
One thing you could perhaps do, since you have no 240vac loads, is to split the loads and not pair those two inverters in a system.
Just let each do what it can do, individually.
Could they then be calibrated to accept the same sine wave? Because I am mobile my sources of power can change. I am predominantly off grid relying on solar and lithium so split phase does work well for those times. But I would like to maintain passthrough and charging with both units. The outputs are not wired in parallel and would not function correctly if they were and I were to plug into a split phase circuit. Doing a reconfiguration in the inverters would be easy when changing power sources. Rewireing the inverters would not be an option.
Hi, they would not need calibration to accept the A-C input sine wave.
Note that breaking their link; which is what I’m suggesting; does have some other side effects: you’d need to rewire the lithium protections, and in case you have monitoring like a DMC or CCGX, that will change as well. It’s all possible, but gets a little complicated and not very common.
From Victron we won’t be able to help in all the details with this; best option I can recommend you is to find a trained and experienced installer.
Thank you for your responses. The functionality that I am trying to obtain is actually becoming more common here in the United States with the RV community. There are many of us that are currently living full time in our RVs that bounce between complete off grid situations and partial to full hook up RV parks. Your victron products have become more popular do to the connectivity of a total package. For the most part the dual inverters wired in split phase work for most situations except when the RVs are powered by most onboard single phase generators or connected to 30 amp service. (More)
Does Victron have a list of trained installers that will be able to get the results I am looking for? So far everyone that I have made contact with has said that they have made a request to allow the full functioning of the inverters but that they did not know of a work around other then rewiring the inverters to only give functions in parallel. Because it is still only giving the ability to operate in parallel, it is not a viable solution either. How does the follower know not to turn on the passthrough relay when it is not receiving power 180 out?
I believe you can configure both of your MultiPluses in parallel and feed them only L1 when you are on a 50A 240VAC park power pole. Set the shore current limits appropriately, and you can charge and/or pass-through at up to 4800W (80% of 50A at 120VAC) total.
The number of times you would otherwise pass-through more than 4800W (which you can only do with your two Multipluses in split-phase stacking) is very small if you have a typical RV. For those rare times, the power assist can cover your momentary peak load.
Obviously, this configuration works fine for 30A, 20A, and 15A shore supplies as well.
This is what I believe is happening when in parallel. Because the outputs of the inverters are not wired in parallel, the master is being misled. If both units are powered and charging at the max output and a 1200watt load is applied on L1 (master) it will overcompensate by shutting down both chargers and carries the load until the generator is then reintroduced. If that same load is applied to L2 (slave) it appears the load is not reacted to by the inverters and the load is carried immediately by the generator. The generator output is also not capped at the maximum set on the inverters.
A typical day in the RV can vary based on location but may include running two ac units while doing a load of laundry. Some days it happens while being plugged in to 50amp service in an RV park or a 5500watt onan generator supplying single phase power at 45 amps. It could also be running one ac unit while power is being supplied by a small inverter generator that is putting out 1200-1700 watts depending on elevation. When coupled with a 1400 watt solar supply and 7.9kw of lithium batteries, it can be stretched through the hottest part of the day.
I know I'm late to the party here but I figured i would chime in since I have a very similar setup. I have a motorhome with a 50A shore connection that hooks up to 240v split phase and feeds that to two Victron inverters (5kva Quattros in my case). The Quattro's are configured to run in split phase and my Quattro's are also connected to a 6KW generator which only puts out 120v. (More on that later)
These are tied into a 48v 200 AH Lithium battery (Roughly 10 KWh)
In my case: When I connect to 120v shore power (Such as a TT-30 (30 amp) RV outlet) the adapter that converts from 50 to 30 amp simply connects the one hot leg of the 30 amp outlet to *both* legs of the motorhomes electrical input. When the Quattro's see they are getting a Sine wave that is not as they expect (They expect 180 degrees out of phase, and this gives them 0 degrees out of phase) the "master" inverter connects to the line and the "slave" inverter simply refuses to connect and continues acting as an inverter.
The only real *problem* was the generator. Sure it could work the same as being plugged into a 30 amp 120v outlet, but a single Quattro can only charge the batteries at about 4kW max (Less when they get warm). Since I have a 6kW generator it's not running most effeciently at the only 3-4kW the single Quattro would draw. In order to address this I added an Autotransformer (Victron offers one but I ended up using the Outback brand) to convert the output of the generator to 240v split phase. Now when i fire up my generator I charge my batteries at the full 6kW available from the genset.
Nice setup. Do you have 240V circuits on your rig?
If not -- and most RVs today are set up this way -- you can stack the two inverters in parallel and avoid having to buy the autotransformer.
I didn't have 240v circuits originally, but after adding the inverters I have taken advantage of the fact that I *always* have 240v service in the rig to upgrade things like stovetop, water heater, etc. I even added an external NEMA 14-50 for charging our Nissan LEAF that we tow behind the motorhome.
You're right: I could have stacked them in parallel but then we have the opposite problem: If the inverters are configured for parallel operation the "slave" will refuse to accept the L2 power leg when connected to 240v service.
Basically:
1.) If configured for parallel the inverters work together on 120v but not 240v.
2.) If configured for split phase the inverters work together on 240v but not 120v.
So you have to pick #1 or #2. For me it was easier to go with #2 and add the transformer to step the genset up to 240v.
Regarding adding 240V circuits, awesome. It is nice to be able to do that, if you're up for it. I'm surprised you were able to pull the needed 4-wire runs needed to run most big appliances, however. Did you gut your RV?
Regarding paralleling inverters, I don't think #1 is true if you just parallel them on L1. You just set up your rig to only accept single-phase shore power, any of {15A, 20A, 30A, 50A}. On the output of your paralleled inverters, you put your autotransformer to step up to 240V and make the split phase.
That this is relatively easy to do is why I don't think Victron will bother to make auto-switching a priority -- it's too easy to work around.
Btw, my understanding is that North American marinas also have this identical dualing shore supply issue -- 50A split phase and 30A single phase are both common, just like for us landlubbers. So the market is not that small, I guess. Except most are not going to run stacked inverters in the first place!
To further clarify why I suggest just using L1, basically there is no RV that actually needs the 9.6kW available on a typical 50A/240V shore circuit, because those of us who might actually create those kinds of loads already have large batteries available to peak-shave.
My RV is the most power-hungry one I've seen, and even the 70kWh I can take from a single 30A/120V circuit over the course of 24 hours exceeds the maximum energy I could consume.
The real issue is if you have a very large 240V generator... then, you could run out of headroom on a 120V input for charging. But this is mostly a theoretical problem for 99.9% of RVs.
"basically there is no RV that actually needs the 9.6kW available on a typical 50A/240V"
You haven't seen my rig. I have replaced nearly every propane powered appliance with electric. Electric stove, convection oven, dishwasher, water heater, refrigerator, etc. Add in two roof air units and you can easily hit 10kW. I can easily exceed the 5kW available on a single leg of a 50 amp circuit.
Furthermore: Running on only 1 leg creates a major imbalance on what is supposed to be a fairly balanced circuit. On my previous rig I did exactly what you described: To simplify inverter wiring I only used a single leg of the 50 amp shore power leaving the other unused. The result was I routinely tripped breakers at RV parks by pulling sometimes as little as 28 amps. I also found that the voltage on L1 would drop considerably in such cases (From 125v to under 110v) before the breaker would trip. It was a major hassle and a mistake I decided not to make again.
My rig is more power hungry than yours (I have four roof airs, 10kW of heating elements, 240V appliances, 18kVA of inverters, and a 20kW generator), and an entire day's load even on a warm day is still under 80kWh. That's why I'm confident that it can be done on any RV, as long as the battery is large enough to smooth the demand.
Breakers in RV parks, however, are notoriously weak. They were not designed to be used as on-off switches every day, and they get worn out and the boxes get hot in the sun and these things combine to make them trip early. But even the worst ones I've encountered (also about 28A, but I'd have to check my notes to be sure) still yielded 80kWh per day, which again is plenty with a big battery.
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The sag to 110V on one leg is a non-issue in my experience. 8% more current is a rounding error. The issue there is the heat and the worn-out breakers.
A big issue in some RV parks is when 240V is actually 208V because they are running the legs at 120 degrees. Then the pass-through to 240V appliances can become a concern.
I must admit that I'm quite confused now. If you have 240v loads, 18kVA of inverters and a 20 kW generator... What could *possibly* be the advantage of leaving the 2nd leg of 240v service unused, especially when you have 240v loads?!? Sure you can get by with it... But why? Just use both legs. They are there, why not use them? I'm just not understanding why you're pushing so hard for this 1 legged approach.
Especially if you have 240v loads: That means you're taking 1 leg of 120v, sending that to all of your "parallel" inverters, and then using an auto-transformer to step their 120v output to 240v?Are you also only using 1 leg from your generator? There's no way a 20kW generator is only putting out 120v. That would be nearly 170 amps! What make/model is your generator? I just did a quick search and cannot find any generators that size that are 120v only.
I'm only advocating for the single leg approach when the RV has only 120V circuits and a 120V generator -- as discussed up thread, by the OP, and in my answer earlier. Most USA RVs are in this set.
I'm using the consumption data from my RV to show, however, that even with a much larger setup there's still enough energy coming from a small 30A/120V circuit to meet the average demand.
Once 240V loads and genset come into the picture, it makes little sense. (And, to answer your question, I chose to use a 240V inverter and a transformer to step back down to 120V.)
Does that makes sense?
Not to beat a dead horse, but I'd like to voice a simple 'me too' for irwinr's use case. (I've built my system similarly described in '#2)' )
I too run twin Quattros and regularly consume 6kw+ of power, or more when on shore power, or simply more than a 15a or 30a circuit can provide.
I too regularly either use 50a shore power, or my 5500w (49a) 120v Onan and want the ability for both inverters to pass through & charge when only a single leg of input is present (across both inverters).
When I go to inverter mode, and run on the generator, I can only get ~30a on leg 1, having to invert L2 when I would prefer to get 24a through each inverter, and boost as necessary.
To help with my own situation, I too have just commissioned a hand built auto-transformer from EPD in North Carolina to effectively convert my 120v genset to a 240v generator to address this issue as the Victron Autoformer would not like imbalanced loads greater than 20a.
Basically, I too have the same problems that irwinr explained and am using the same solution to address them due to what appear to be Victron's software based shortcomings. (Add mine to the pile of yet another use case, and I know of 2 other guys who are in the same position.)
If Victron would allow for either same phase or split phase inputs into their inverters it would solve ALOT of problems.
(I believe that Go Power figured it out with their IC 3000 series inverter/chargers)
Hey all, believe me, I also whish we could make the inverters work like that real soon. The issue is limited amount of qualified software (& hardware) developers.
Especially when it comes to the software in the MultiPlus we have a long and vast list of things we want..
However I do think there is a solution; not automatic but requires a manual intervention by the user: since a while, a GX device can read and write the settings of the Multi/Quattro system; which includes their splitphase vs parallel configuration. This is done with a call on the commandline. It needs to be tried to know for sure, but I think its fairly straightforward to make the Gx device store two sets of settings, and swap between them with the press of a button. It includes a short power outage; seconds; thats the down side.
Please let me know what you think.
And, If there is anyone out there thats interested in implementing this; paid or unpaid; please let me know.
Hi mvader,
While I completely understand the issue of limited developers (I work in software myself) I must admit I am a bit puzzled about the complexity of this particular problem.
The reason this puzzles me so much is that the Victron units already allow for floating phase. When you enter the system configurator it allows you to choose "L2 floating" which means that L2 doesn't have to be exactly a particular phase angle. It allows it to "float" from say 120 degrees to 240 degrees. (I've been told it can float 60 degrees either direction)
That means that these units are *already* set up from a software and hardware perspective to allow the phase of L2 to change without doing any configuration changes to the units. The only issue is that it only allows up to 60 degrees of "float". It seems like it should be a trivial software modification to simply allow them to float up to 180 degrees (or more) rather than limiting the amount of float to 60 degrees.
On the same topic: 6 or so years ago Victron offered a single Quattro unit that solved this problem without even needing to have two Quattro's at all. You guys offered a single Quattro unit that could accept 2 AC inputs that were either the same phase or split phase and it would automatically switch between the two. At least that's what the owners manual for that older unit claims:
(See page 2)
I'm sure there are good reasons. It's just hard as a consumer to understand why these features used to exist in older (discontinued) units and why the current units features seem arbitrarily limited to 60 degrees of phase angle float.
mvader,
Thanks as always for your quick replies. It helps knowing that somebody at Victron understands our needs/wants.
I might be interested in a 'quick switch' of Quattro settings config via the CCGX. Though my time to test is quickly coming to a close as I expect my transformer to be fully implemented end of next month.
I will certainly help with testing this option. I unfortunately do not have the software development skills but I do have a dual 12/3000/50 setup in my coach that does get used with various shore power connections. A short cycling would not be an issue for my situation. Please let me know if you would like my assistance and I can send you my direct contact information.
I know this is an old thread but I'm in a similar situation now and have done some exploratory work on this.
If you set them up in parallel (with power assist enabled) despite them both feeding branches that are not bonded together (because normally they're isolated since they have a 180 degree phase offset), then when a big starting load like an air conditioner kicks on, you'll likely get an overvoltage fault on the side without the air conditioner because both inverters will boost their voltage to compensate for the starting load. But of course only one of the bus bars -- the one to which the air conditioner is connected -- is experiencing a voltage drop, and hence the other one, since it's getting the same voltage boost, will experience overvoltage. Fail.
I'd very much like to find a workaround for this that does not involve purchasing additional equipment. There's no fundamental reason why the two inverters can't operate independently, and accept both 120 and 120/240 input. And with the Multiplus 3kva (the ones I have) the maximum charging current is 120A which means that if you simply let the first one switch to grid with the second one inverting, you will not be able to pull more than about 1300 watts on L2 without the battery discharging (after conversion losses). I'm very disappointed that after spending all this money this basic capability does not appear to be available, especially considering the complexity of the software.
You could use the same transformer for shorepower I'd think? saves losses from AC-DC-AC conversion (and adds a bit of standby use from the transformer)
In theory: Yes. But the wiring needed to accomplish this gets complicated fast as it would require a transfer switch between the shore power, generator, transformer and slave inverter.
Certainly doable but for me the benefit simply wasn't worth the cost and wiring effort and space that would be lost due to the extra components and wire runs needed. I ended up removing the transfer switch that used to e in the rig to switch between generator and shore power. Now the Quattro's themselves act as that transfer switch. In the space where the old transfer switch used to be is where the autotransformer now lives. There are still losses in the transformer too so if you compare the AC-DC-AC losses with the transformer losses the transformer would only be slightly more efficient.
I am not sure why it has been and continues to be recommended to permanently modify the RV to parallel the inverters. The inverters are smart enough to know when they are 180º out from each other, why can't they just be told to accept that they are on the same phase. It is not uncommon that people bounce between the two situations. But regardless, I still can not understand the reasoning to permanently limit yourself to a single leg of 50 amp service when plugged in unless you were consistently on a single phase output generator over 3000 watts. This is what my CCGX looks like when I am on a 50 amp pedestal. I do not have a large onboard generator so it doesn't matter as much to me in the grand scheme because the way it is now, it all works out for the better. Obviously we are just small fish in the Big Victron pond. But if anyone hears of a hack, please let me know.
I agree with you that the inverters *should* be able to easily switch between split phase and parallel. I argued with Victron engineers for months over this before I finally just settled for the split phase approach.
To be clear though: I never "recommended to permanently modify the RV to parallel the inverters." That's the opposite of what I suggested. My suggestion was that you keep the inverters in split phase (Some call this "serial") rather than parallel. This way you get to use both 50A legs of the 50 amp service.
With this configuration on 30 amp service one inverter will not pass through... But in my experience I haven't really seen this to be a big deal at all. You have full 30 amp service on L1 going to inverter #1, and the 2nd inverter powers leg #2 from DC energy that is provided by the charger from the #1 inverter. You do have some efficiency loss going from AC-DC-AC on inverter #2 but I wouldn't consider it enough to be a major problem.
I did not get the feeling that you were recommending the parallel. I have kept mine in spit phase also as it is more likely that I would be plugged into 50 amp or less than 15 when mooch docking or running off my small generator.
I'm not sure I follow your reasoning vis a vis being "consistently on a single phase output generator over 3000 watts." What does that mean?
I also don't know what could be "permanently modified." Can you clarify?
My experience when running parallel and they are not wired in parallel, they still act in parallel which messes with the GFCIs and causes the chargers to react in unison. So if you have a 2400 watt load on L1, it will cut back the charger on L2 because it thinks the two inverters are carrying the load. So the only way to get them so they work right is to permanently wire them so the outputs are tied together and there is only one hot line in.
So my comment about being on a generator that's single phase and over 3000 watts is that you can not get full use out of the chargers with anything less so there is no use wiring your inverters in parallel to take advantage of it unless you were in that situation on a regular basis. I am full time in my 5th wheel and live off grid most of the time. I spent $48 on campground fees last year and that was for dry camping spots in campgrounds. So I use my inverters mostly off grid with a 600Ah Battle Born Lithium bank and 1400 watts of solar.
I am in progress of installing a similar system to my 50A motorhome, but using 2 48V 3000VA Quattros and have a 7.5 KW Onan - which is wired two hot two neutrals plus one ground through a double pole 35A breaker, originially this went through a transfer swich and I am rewiring to go direct to the inverters AC 1 inputs. As per this discussion this means I only will get 1/2 of the generator output available... I was wondering how you wired up your Outback autotransformer...i.e. did you just wire one of the generator legs and then only connect the transformer output that is now 180 degrees out of phase to the AC 1 input on the second Quattro? I assume this will be limited by the autotransformers neutral phase continuous current limit - about 30A so should be ok for me. Regards Colin
