Multiplus ii 5000va Configuration Options

Q&A and troubleshooting
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Hello all,

I’m about to add a Multiplus ii GX 5000va and Pylontech batteries (1 x US5000, with more to follow) into my existing system, which currently looks like this:

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As I understand, from reading the Victron documentation and this forum, there are LOTS of different ways to connect the multi and I’m getting bogged down in the options and max loading stuff!

I think the simplest option (option 1) is what I’ve seen people refer to as ‘singled legged mode’ ? where only AC IN is connected to the consumer unit and it bidirectionally can support the loads and charge the batteries etc.

However, to get the full functionality of the multi (option 2) I started to think about using AC1 OUT and AC2 OUT for critical and non-critical loads during power outages.

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Obviously this configuration requires more wiring changes but given my old WYLEX consumer unit is really old, now might be the best time to replace it.

I’ve been following this schematic from a member who kindly shared their setup in their VRM portal (thanks to @Jason - UK)

schematic
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I can see in their design that the AC1 OUT distribution board also has their grid-tied Solar PV, which I’m looking to do also as I guess this means my Growatt inverter will continue to operate during a power outage as it’ll see the multi as the grid?

Questions:

1). Max load on AC1 OUT. Am I correct in saying that this will be the grid in pass-through (50A), plus the multi’s own rating constantly (~ 17A), plus whatever is coming from my grid-tied inverter solar+battery (max 6kw)?

I ask this question as I’m trying to calculate what circuits to put on AC1 OUT? (I have two electric showers). I intend to wire my EV Charger into the distribution panel before the multi, should I also wire my electric showers in here? Should I consider wiring in any other heavy loads at this point?

I want to make sure that during a power outage I don’t exceed the rating of the multi. In a power outage I’m guessing the multi will still provide its own rating constantly (~ 17A) [assuming battery has charge] , plus whatever is coming from my grid-tied inverter solar+battery?

2). I’d like all the loads in my house to be supported by (1) Growatt grid-tied inverter (solar+battery), then (2) the multi and then lastly (3) the grid. Looking at my proposed layout above is this how I should expect the system to work?

Thank you in advance for any help/suggestions.

Chris

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Hi mate quick one if you want the AC solar to go through the multi has to be one to one ie only 5kW can go through the multi without overloading it I would get a bigger multi and save yourself trying to balance devices in the winter ie 10kVA or higher but bare in mind you will need more batteries from the off set and one us5000 is pretty low as the multi does not run without the battery.

And yes the shower 100% before otherwise your not going to be able to do anything if someone is taking a shower with your house base load is going to take your near to your multi’s limits.

If you want to have your AC solar in grid down situation it would have to go though AC1 out which I would only be able to do 5kW. 6kW would cause it to overload. Give yourself wiggle room and get a bigger unit. I have added load to my system especially where ac solar is concerned. If I find my stuff I’ll post it for you to satisfy your own mind and finalise your design ps wylex have a recall on some of there older MCB’s so could be worth changing the CU, my system is a fairly simple one see here Simple UK Home System I’ll post an overview soon this is an old one as I got he DNO to give me approval to go to 14kW here is the simple over view https://community.victronenergy.com/uploads/short-url/xnUIX05L6N8wuxmpmyvvprdDmJN.pdf

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Answer to question one: 50A is total max, this is the max current the multiplus relay can handle

So grid + multi + ac pv

If your current ac pv is 6kw, it can not be connected to ac out 1/2, its to big, so in case of grid failure you only have battery backup

Either leave it on ac in, make it smaller (split it up on 2 ac pv inverters, one on ac in and one on out) use victron mppts, or go for a 10kva multiplus with enough battery

Question 2: if you use energy meters on grid and if needed on ac pv the multiplus can do what you want

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How do you want to control the two battery charger/inverters to work together?

The Growat hybrid and the MP2 will both try to manage a grid set point if there is no central management.

ACin and ACout2 cannot be connected to the same circuit. Either connect non-critical loads directly to grid and parallel to ACin. Or connect it on ACout2, which counts into the pass through current.

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Thank you @Daza , @DuivertNL and BjoernK for your responses. Clearly I haven’t thought this all through properly and I have the kit which I can’t return (not easily anyway), so I need to try and make something work.

My original requirement was simply to compliment my Growatt inverter to support heavier loads (the Growatt can only discharge from battery at 3kw max, note: this is when there’s no solar).

With my original requirement in mind, will I be able to get away with just running the MP2 in ‘singled legged mode’ (AC in only connected)? This will do what I originally set out to achieve, right? If so should I connect it into Main Consumer unit or 2nd Consumer unit? And I assume a CT or EM112 will be required? Anything else I should consider?

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@robovanbasten

From AC Point of view, you can connect the MP2 via ACin parallel to your loads and Growatt or you can put critical loads behind the MP2 limited to 50A while grid is there or 5000VA / 4000W while grid failure.

If the Growatt would be a PV-inverter without battery charger/inverter (no hybrid) the answer would be simple.

You should find a way to manage the two inverters (Growatt hybrid and MP2) to work together. Both might try to achieve a certain grid set point, e.g. 0W grid. If PV increases, more energy is charged to battery. If loads increase more energy is taken from battery. Without central management, the two control loops / independent management systems might work against each other.

Simple solution might be disconnecting the battery from the Growatt. It is a high voltage battery and not compatible with Victron.

Other option would be to dig into ModBus RTU of the Growatt and program external control with NodeRed a the Victron GX.

Maybe there is a home energy system in the market which can control these two energy systems together.

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No you can’t connect multiplus over to 2nd CU as your crossing in put out output there would be a big bang :collision: say this way as I think you will be pushing the limits of the multi say 2nd CU is your heavy loads and the main is now purely just on the multi and the solar connect to the Henley block run a CT to the Henley for the multi and tell it on the ESS that solar is connected there inorder for it to balance and draw from that at the same time but I think it’s going to require a NodeRed solution or Home Assistant but makes it really complicated and at some point you will get them looping to balance themselves.

Personally if you could return it I would take it from someone that got a5kVA now has a 10kVA it makes adding upgrading and ultimately not changing your power draw habbits in your house hold as you’ve got to worry about the people that just start turning stuff on with not a care in the world till all the alarms start :pensive_face: 10kVA would be the master and the 6kW could just go through the ac1 out.

Only way I see is having them as two systems mains cu so Henley into Multi into main CU. Grow watt just powering the 2nd CU and these will need to be isolated from each other ie no shared neutral between CU 1 and 2 your going to give yourself a headache and also keeping that spark fully employed :wink: £££££ to do that

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@Daza , @BjoernK , my original inspiration came from reading this post –> Multiplus and Hybrid Solar System - VictronEnergy

This guy seemed to have done what I wanted to do so I hit the buy button to get the kit. Please can you take a look at that post, what am I trying to do different?

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Yes it’s what I said the grow watt is used as a slave his unit is an 8kVA and only got a 3.6kW unit on the back end of AC1 out theoretically they could have an 8kW grow watt unit there and it would be ok, your problem is the unit is two small for your 6kW grow watt to go in that position.

If it hasn’t been installed and not long to getting the kit plead your case with the supplier who may charge a restock but at least your would be able to achieve what you want from the system.

Ie the additional boost of AC from both devices so with an 8000 and the 3kW from the grow watt as AC that’s 11kW useable AC an 8000kVA is the lowest powered unit at the moment as I’m sure there is a 6kW unit coming but give yourself the head room, PS sorry you had to find out that this isn’t possible like this before you pulled the trigger

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In the linked threat the writer says he has interfaced the LuxPowr hybrid - your Growatt - to Home Assistant (HA) which does prediction. Though HA is the external controlling energy manager. If you can steer your Growatt from HA and will do the same with Victron, then it should work.

Victron and Growatt support ModBus, but you need to dig deep and program the control loop.

With Victron you can set a set point based on the Energy Meter. This is either an external or the MP2 build in one. With only one phase, you can put a CT clamp on the MP2.

Though:

Put an energy meter to measure grid which es evaluated by HA. Connect MP2 ACin parallel to your Growatt 6kw as it does not satisfy 1:1 rules. Connect critical loads to MP2 ACout1.MP2 is an USV. Use the internal meter. Connect non critical loads which can exceed 50A in sum parallel e.g. to MP2 ACin.

Interface with HA to Growat and Victron. Calculate in HA which system shall provide how much energy into your house or store into battery.

If you set negative set point on MP2 with the internal meter, it will supply energy to your. On critical loads.

The set point for the MP2 shall. It be set to frequently, e.g. once per minute. If loads on ACout change, the MP2 will react immediately to hold the set point.

Hope this helps.

There are many discussions about coupling either two Victron systems or one Victron with another brand. I haven’t seen posts showing a solution.

If you do not want to have a third system (HA), than NodeRed on the Victron GX might be an option.

Maybe it just works without managing the both together.

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I may have missed this bit but give us the spec of the grow watt at full power AC side ie with full sun and battery power what is the max kW AC the unit can put out? If it’s 5kW or below you can do exactly the same setup as that person that posted that. Are you able to read the spec of the grow watt and share it to see if it can go ac 1 out would save you a lot of pain. * EDIT * But without knowing the exact model online I looked at a few grow watts and they are 6kW which will rule out configuring it AC 1 out without a bigger multi

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Hi @Daza , thanks for your response.

I have a Growatt SPH6000. See product label below.

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It has 2 MPPT’s, each string has 8 x 385watt panels, so ~6.2kw total. The inverter is rated 6kw max power. The max discharge from the batteries is 3kw. Therefore 6kw can only be achieved from a mix of solar+battery, or just solar on a really sunny day. At night time the max is just the 3kw from batteries.

If you look at the schematic at the top (from @Jason - UK), he has a 6kw SOFAR SOLAR inverter on AC1 out, can’t see how many panels are feeding it but I think its 8 x 360watt on each string, so that could be potentially 5.7kw? He has a MP2 5000va, I wonder how he’s getting away with this :thinking: ?

Back to your response above, I think you’re basically saying that the MP2 needs to be bigger than my Growatt 6Kw inverter? Which MP2 would I need:

Victron MultiPlus-II 48/8000/110-100 230V (6500W) or Victron MultiPlus-II 48/10000/140-100 230V (8000W) ??

Chris

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Hi mate yes I checked again in hybrid mode that can output 6kW so over what the Victron 5000kVA can handle. Don’t get bogged down on how many panels Jason has as you can always make an AC PV inverter Clip ie my 3kW Solis inverters can have 4kW of solar panels but the output would always be 3kW as that is the max output of the invert the rest is gone in heat. The reason Clipping is done is to get the inverter generating power earlier and later in the day as the array is oversized minimal light will keep it turned on.

Chris either the 8kVA or the 10kVA both will work as they are over the 6kW but the 10kVA would give you more versatility but does require more US5000’s to start bonus is the Amps charging if you do every expand like I found myself starting to do you can charge 8 of the US5000’s in a 5 hour window :wink:

£90.50p difference 100% 10kVA is the way to go in that scenario

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Hi @Daza , ok sounds like from what you’re saying I need to go bigger on the MP2, and 10kVA is probably best (like you say its only a bit more expensive than the 8kVA). THIS IS ASSUMING I CAN RETURN MY UNOPENED 5kVA MP2

Here is a revised proposed layout, does this look ok? It shows my Growatt inverter on the back end of AC1 out. I’d have all my heavy loads such as Zappi and two electric showers before the MP2. I’ve drawn in a non critical consumer unit on AC2 out but I probably don’t need this as I will have everything going through AC1 out (I assume the 10kVA can handle it?). Also added a Cerbo GX as I guess I would need one of these now.

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If I get 10kVA model what is the minimum number of US5000’s it needs? I only have 1 at the moment! This is getting expensive!

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@DuivertNL, above you said “leave it on ac in” as one of my options?? :thinking: Given the other responses here do you think that would work? Chris

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As you have heavy loads grid parallel on ACin like the Zappi, add a CT clamp or energy meter for the MP2 to get grid measures. The MP2 will try to get hold the grit set point, e.g. send energy to your heavy loads.

You can also try to get the grid and PV data from Zappi or Growatt via network into Venus OS.

The MP2 10k shall be fused 400A. It can be connected with 2x 50-70qmm each fused 200A.

I recommend at least 4x Pytes 5kWh batteries or equal, e.g. 400Ah+.

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Yes it will work altough controlling is a challenge, as said both systems would like to measure grid and wont see each other work, so i think you will have to do some node red programming to get it to work properly as Björn Kellermann already stated

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Regarding my Growatt inverter, I do have the option to throttle it back to lower output, say 5kw (I can do this in the inverter settings I’m sure). Does this help my situation/give me other options? I’m not in a position to buy another 3 x US5000’s for the 10kVA model :frowning:

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You can also limit the MP2 10k with DVCC load and discharge current. With that you have the option to add batteries later.

If the Growatt is on ACin, there is no need to throttle it. The factor 1:1 rule applies to grid failure when the MP2 needs to charge all energy into batteries while increasing frequency to make the PV inverter throttling PV production.

Pls double check your Growatt supports frequency shifting also known as frequency watt. At 50.2 Hz it shall start reducing power linear. Latest at 53 Hz it shall throttle to 0W.

If the Growatt is on ACin, it will be disconnected on grid failure. On ACout1 it would continue supplying your loads and charging the MP2z

Pls check the charge current limit for the US5000. Usually 0.5C, e.g. for a 5kWh battery at around 50V it has 100Ah meaning 50A charge current limit. Though one US5000 might be charged at 2.5kW normally.

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You could get away with 3x US5000 max charge is 46.6amps so in spec for charging the pylontechs but 4 is ideal and I recommend single extension wires for each means you can charge and draw at the heights rates. Spec 50amp charge discharge so just over the 140amps from the 10kVA for three but buffer is 4pylons

You would have to decide if you want the multi to try and cover the input side as well but that can be done in the configuration as long as you run and wire/ct just in case you want to later. @DuivertNL looking at the spec it still outputs 6kW in AC mode according to spec. OP could use it on AC in but will leave 1kW on the table that multi can’t use and won’t have it as additional AC ie in grid down and as a multiplier on AC1 out ie the 6kW and the 8kW (14kW)