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cascading inverters

Can I chain Multiplus and use Power Assist to have more power ?

I find it hard to get information on how the Multiplus works. I own a Multiplus 48V 5000VA 70A and for a long time I thought that the maximum current draw from the battery was 70A while it seems it's in fact close to 105A (5000/48). I also thought that the maximum output power was 4000W(5000VA) but on the enclosure it's written "AC transfer capacity 100A". Can the Multiplus deliver more than 4000W if it has its AC input providing the needed power to compensate?


My goal is to extend the system because I am frequently overloading it but I cannot extend the battery pack because I don't want to mix different batteries together. I'd prefer to create a second battery pack. Something like in the following schema :

[image]


The second multiplus having a n AC transfer capacity of 1000A, it is more than enough to transfer the 4000W from the first Multiplus and produce in addition to the second multiplus inverter a total of 8000W.

Will this work?

What can make the second multiplus overload?

mildred asked
kevgermany commented ·

1 Answer

more output power needed for off-grid system with a multiplus

Hello, I am a leader of a boy scouts group in Belgium and last year I got the chance to build a portable solar energy unit which will be used for our summer camps to power fridges, lights and charge electronics.

This unit consists of solar panels, a smartsolar MPPT, a lead-gel battery bank and a victron multiplus 48/1200/13-16 inverter. I also added a raspberry pi running the venus os software to amulate a GX device. This raspberry pi is connected to the MPPT and the Multiplus using a ve.direct and ve.bus cable.

The setup works great, but there is a problem of having only limited output power and peak power (1000W and 2000Wp) because of the relatively small multiplus choice. This caused the inverter to sometimes turn off when too much power was drawn from it, for example when turning on multiple fridges at once. To remedy this, we are looking to upgrade the output side of our setup by adding an additional inverter. What I currently see as possibilities and their limitations:

- Adding another multiplus 48/1200/13-16 in parallel. This would be the cheapest option and would double the output power and peak power. However, as these small multiplus devices have only 1 ve.bus port, I would be unable to daisy chain both inverters together and to the raspberry pi, so I don't think this would be an option unless if I step away from the GX functionality.

-Adding a Phoenix inverter to the battery bank: As this would lead to a totally separate operation from the multiplus, this would lead to 2 separate AC output: one high power from the Phoenix and one lower power from the original Multiplus. This is quite confusing for people not familiar with power electronics who will be operating the mobile energy unit in the future. It also makes the original Multiplus quite redundant as the phoenix inverter will probably be capable of running the whole all the loads. This would make the Multiplus into an overqualified battery charger, only used to charge the batteries before we leave for the camp using the grid. This would also be more expensive than the other option.

-Not sure about this one, but I read about cascading inverters and I am wondering if I could cascade two multipluses together without linking them with a ve.bus cable. The first multiplus would take power from the battery bank and supply it to the second multiplus. The second multiplus would however have to be configured to not charge the batteries and only discharge them, because otherwise it would create a loop of charging and discharging the same battery bank. I'm also wondering if the output power of the second multiplus is limited to 1000W continuous, or if this 1000W is only the power it can draw from the batteries and, once supplied with input power, the total power it can deliver increases by the input power amount.


As you can see, all of these options have their downsides and I would like to know the thoughts of some people more familiar with Victron products on them, as well as maybe some other suggestions?

jowan asked
shaneyake commented ·

2 Answers

Multiplus or Quattro in parallel cascade - How do they operate to cover increasing loads?

Just for the sake of clarity... ( i thought i understood this - but as ever the info is grey or not specific)

Multis or Quattros working in parallel for a larger output capacity. (single phase)

Do the paralleled units mirror each other and operate in the same fashion

or

Is it a cascaded arrangement, where the master is loaded up first, then the second unit starts to come in to cover the load... and so on....?


And then so.....

Shore / generator AC input

Can this be connected to the Master alone , or does it have to connect to each paralleled unit ? (there are schematic examples for both arrangements - ie. two AC sources, but then other information "infers" symetrical connections required.) There is the note about the shore power setting needs dividing by the number of conencted units.


Thanks

Chris

Chris asked
Alexandra commented ·

8 Answers

Cascading 2 Multiplus with two battery banks

Can I feed the second Multiplus into the AC IN of the first multiplus. I do have got 2 different battery banks with individual solar chargers and 2 multiplus. What configuration is suggested?

Is there a possibility to limit the AC OUT from the second multiplus goiong into AC1 from the first one?
(I do not need to get more max AC power out, just using both battery banks )

Thx for helping!

abaco asked
pbilka commented ·

2 Answers

Upgrading with a second PV system - What are the possible and valid variants? (Parallel, cascading...)

Hello there!

I would like to propose a game for Victron experts and enthusiasts who are reading this post. Let's imagine we have a typical PV system with panels, batteries, an inverter charger, loads and the presence of the utility grid. If, at some stage, we want to keep the present system (which is not too old, and its size is not small, not too large) and add a second system of similar size or even larger than the first one, what variants or possibilities would be the most optimal/advisable or more advantageous? Which ones would be valid, but not advisable? Which ones are not technically possible? I know it is a bit of an open question, but it would be interesting to read all opinions. Please take it as a game.

As a general guideline the aim is to increase the size of the system, while keeping the original one. Loads should still be supplied in the case of grid failure. Excess energy can be fed or not to the grid (up to you).

If you like you can give opinions based on the following diagrams (I believe they are all self explanatory, but if not please ask). Number 1 is the original system. For the others, in red the system I believe is not possible technically. In purple a system I believe has little benefit, but still possible. In green all other viable possibilities. For these, subindexes 1 and 2 do not mean 'original' and 'new' inverter - please feel free to place every inverter/charger in the position you like.

I know its obvious, but here you have the meaning of each letter (panels, charge regulators and grid-tie inverters are not depicted in the diagrams, in order not to add complexity, but both AC and DC coupling can be considered for any or both of the inverter/chargers).

U stands for Utility grid.

I stands for Inverter/charger (Multi, Quattro)

L stands for Loads

B stands for Battery

And of course please let me know if I am wrong in any of my assumptions!! :)

Cheers!

[image]

mm-azimut360 asked
machined answered ·

2 Answers

Victron MPPT 100/50 connected to Ronegy 3kw Inverter Charger

I have a pair of Ronegy 3kw Inverter Chargers drawing from 4 12 volt banks of Ronegy 200AH AGM's I have also 2 300 Watt 30V Xunlight flexible Panels connected to a Combiner feeding a Victron 100-50 MPPT. The Batteries are split up into two banks of 12v 400AH and each inverter charger draws from a 400AH bank. I am using the 300 Watt panel to provide a trickle charge when the system is not in use as the vast majority of the time the system is connected to shore power or drawing from a generator providing split legs of 220. L1 into Bank 1 and L2 into Bank 2. I wanted to be able to combine the battery banks using a change over switch to share the combined capacity of 800AH. Should I add an additional MPPT to the second bank or can I provide trickle charge from one MPPT to both banks ? The System is basically a Big UPS that keeps the electronics powered in a Trailer until the generator comes on line in the event of power disconnect. The solar is purely for a maintenance charge when the unit is not in use and not connected to shore power and not in operation.


Any suggestions would be welcome


Many thanks

dvcpro50 asked
maxxpwr answered ·

1 Answer

Multiplus 3000 stacking to create 240v without auto transformer

Can two Multiplus 3000 inverters be installed as master and slave to create 120/240v with out the use of an auto transformer?

andrew-fjeldsted asked
Daniël Boekel (Victron Energy Staff) answered ·

1 Answer

Expanding an off grid system

Hey all!


New to this. Have an off-grid system with a Phoenix MultiPlus Compact 24/1600/40 and 4 Victron AGM 12V 220Ah. 2s2p. This is equipment from 2008 so the batteries are getting old. I ordered some 2V traction batteries to replace them. I would like to have more power though...


So I was thinking of buying a MultiPlus 48/5000 to use the old AGMs in a series setup until they are completely dead and replace them later on with more traction batteries. I would also buy extra panels and extra MPPTs to be able to charge everything. I would connect all the solar to the 48V AGM battery bank and its 48/5000 and wire the AC-out of the 48/5000 to the AC-in of the 24/1600/40. A cascading setup. Can I do this? Or would the 24/1600/40 try to charge the 48V battery through the AC-out of the 48/5000? Can you disable this? If I also buy a Venus GX, could I monitor and control both with one device?

Any suggestions?

stijn asked
Elimac commented ·

3 Answers

Cascading inverters

Already posted this at Victronlive, but it seems like that is transitioning to this forum, so posting here as well.

I have an existing 48V 5kVA Quattro fed DC from 13.5KWp PV and 1200AH battery bank.
Power cuts are not infrequent and I have islanded some essential loads to be purely fed from this system.
I want an offgrid system, and I'd prefer not to add ESS unless I have to.

I want to add another identical Quattro to the system and add some less essential loads.

I understand how to conventionally parallel them.
And that it will effectively give me a 10kVA Quattro, but only the same features as I already have.

Q1. I would like to know if connect them in and upstream -downstream relationship would that give me the ability to have 10kVA available at the downstream inverter and the ability to loadshed one of the AC outs if my battery SOC was low. As I now would have 2 AC outs.

Q2. Would this also give me the ability to have a second battery bank that be configured to use a different DOD?

I realize the downstream inverter should not feed back power to the upstream inverter as the downstream inverter will not respond to a frequency rise like a Fronius PV inverter, if the upstream battery bank was full, the feed-in power would have nowhere to go.

Q3. Assuming this configuration is feasible. Would it exclude the addition of a Fronius PV inverter on the respective AC out of both inverters? I may add 5VA of PV inverter at each level of AC out, (1:1 rule applies), but because the everything is synced at the upstream inverter's frequency, it would appear that the 1:1 rule is now broken, is this permissible in the settings?

Q4. Assuming a single battery bank and no additional PV inverters, for the moment are there any special setting requirements and which assistants would be best suited to achieve this?

Thank you

Phil Gavin asked
Phil Gavin answered ·

5 Answers

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