Like this:
Deleted my previous post, I realised the next āstopā is at the fuse. So youād double up from the battery to the fuse, and then from the fuse to the rest of the system, simply ensure you are using cable that is thick enough. Iād say 35mm^2 should be ample. TTT would say use 50mm^2 for everything including your bedside table lamps 
And again, you could do all of this, but if there is a bad crimp in there, you will have a ripple. I would still expect it to show up on VRM in that case.
@plonkster , thank you very much.
Regards
Hi Vis, I will come and sort you out next weekā¦ I did not find anything wrong with your original installation, but lets make sure they dont have a reason to blame you again.
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Iāve had a Siglent SHS806 handleld scope on my wishlist for some time now. RS Components have a rebadged version of it called the RS PRO RSHS806. Itās a little over 8k. I mention this only because thatās the kind of kit you really need to test ripple on the spot.
But you get really nice USB scopes for not much money that would also do. Your entry level Picoscope (very popular with automotive companies) is under 4k now. Or you can look at some of the Hantek models, now youāre getting down to the 2k side. Or a Digilent OpenScope, around 1.5k.
@JacoDeJongh , perhaps something to consider for the toolbox. And tax deductible 
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Iām in good hands. 
WHAT!!!
You DONāT have 50mm2 for your bedside table lamps?
Iāll let you know, I even install fuses on BOTH cables!
On a serious note.
I once measured my assumed cable return length, from inverter pos to inverter neg ā¦ low and behold, I was just just over 5m, bit here and bit there I added over time for MY convenience, so even I got THAT wrong ā¦ and no, it was not the cause for the DC Ripples I had.
So I studied this Victron note in the manual, and have never looked back - even used the bedside table lamps light to read the manual ā¦ (ā¦ just could not resist!)
Here you go ā¦ now no-one can ever tell me that the cables are in question ā¦
Heās got the 3kva 48V one to the left. So 35 is going to be fine, especially for the short distance from the busbar to the inverter.
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30CM
Will this hold true even if I add more batteries?
Your inverter can only draw a max of 66amps from the battery so adding more batteries wonāt allow the inverter to draw more power, it will only result in drawing that load for a longer period. So the cable stays the same for 2 or 20 or 40 batteriesā¦
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Thanks Jaco.
Once again Jaco De Jongh comes through when needed. Thank you very much. 
The system is up and running perfectly again and just in time.
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This seemed like the most appropriate section for my question.
Please help me understand my system guys, a 3Kva Multi Plus II with 5Kva array
I know its actually a 2400 and will run there all day everyday if it doesnāt derate as a result of heat.
But my understanding is/was as follows:
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with āKeep batteries chargedā or ābatteries optimizedā settings and theyāre full with grid available, the panels will provide everything they can, even more than 3Kva peak at times as the inverter merely acts as a transfer/switch thingy.
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But when power is off, and the inverter actually has to work to invert power from the batteries (and panels) if available, then it will stay within its working parameters of 2,4 - 3Kva and derate if need be.
But yesterday this did not seem to be the case.
Please look at the screenshots and help me understand where my reasoning is flawed, or maybe if there is a problem.
Here, the system was set to batteries optimized life. Full sun on all panels and grid available with my 2Kva geyser on and some other consumers.
Note how the panels cannot supply everything and still goes to Eskom. If the panels cant provide everything for whatever reason, then I was under the impression that the batteries should take up the slack.
Why is this?
And here
Batteries used with full sunlight
Here the sun dips a little and the system takes battery power, but still also goes to Eskom.
The best would have been a new topic 
you should get more eyes on it then as only people following this thread would see your comment.
I think this is where your reasoning is flawed. Energy generated by your solar panels is Direct Current (DC) whereas your house uses Alternating Current (AC), so in order for it (PV- or battery power) to be used by your house it needs to be inverted from DC to AC by your inverter.
The transfer switch comes into play when your house is requiring more than what your Inverter / MPPTs / Batteries can provide at that time. It will then take the AC from your electricity supply / generator and direct that through the transfer switch to help out with the loads.
Although that doesnāt seem to be happening in this case because the majority of your AC loads are before the inverter, but if you had that connected to AC Out 2 you would have seen the transfer switch in play where it can take up to 32A / 7360W to help with the loads after the inverter.
Thatās the same as above. Both your panels and the batteries have DC that needs to be inverted to AC in order for your house to use it. As you mentioned the inverter can invert ~2400W which is what it seems to be doing in this case, but itās using a little bit to charge / top up the batteries and the rest for the houseās loads. If your panelsā output dropped to letās say 2000W then you would have seen the extra 400W coming from the batteries similar to your last screenshot.
In the last screenshot your inverting ~2100W which is a little under the ~2400W, but it might be slightly derating because of temperatures as it was inverting for quite some time, but Iām not 100% sure.
Fredhen think youāve hit the nail on the head with your diagnosis. This makes sense to me.
You are right, do to my specific layout and circumstances, I have no loads connected to AC out 2 (which is what you mean by loads after the inverter). I have the Carlo Gavazzi.
Ok so this is a problem then. I would have to look at a 5Kva unit then or another 3Kva because Iām losing out on what the panels are able to produce.
Pretty much, yes. But just remember that the limit is only for DC to AC inverting. When your batteries are charging during the morning you should see your PV put to good use as that is DC to DC. It might be worth either shifting loads to match the Multiās max or see how much youāre paying to have this load taken up by the grid to see if itās worth an upgrade.
You can either get a 5kVA Multi which can then invert ~4000W
Or parallel another 3kVA Multi which will give you ~4800W total.
Another option (seeing how you use so much during the day from the looks of it) is to add an AC coupled PV inverter like a Fronius Primo on the AC out side. You can however only move a maximum of 3000Wp to the PV inverter due to the Factor 1.0 rule and then keep the rest on a MPPT. You will then be able to get your full 5kWp from your array and the PV inverter will keep working when the grid is lost. (Just take a note of the minimum battery sizes as I see they recommend 4.8kWh of lithiums for each 1.5kWp on a PV inverter)
I guess it all comes down to cost at the end of the day like most things.
I feel like I always need to add a disclaimer to my comments to say that Iām by no means an expert and Iām just stating things based off what Iāve read up during my own research. So maybe make sure from someone like @JacoDeJongh & @plonkster before taking my word for it as I may still be wrong in my assumptions.
I didnāt really study the issue too deeply, but maybe this helps.
If you have the Multi running flat-out at its rated 2400W (grid tied), it needs around 2900W of DC to make that power (cause the fans are running full tilt and the efficiency suffers a bit at this power level).
I see this at my place every day. 2400W of PV incoming, but a small portion is still taken from the battery. If I want to be sure that the battery is not discharged at all, I need to set a limit of around 1850W.
Just remember that your MPPTās amp limit and your batteriesā voltage at any given moment is still your solar generation limit. So even if you get a 5kVA multi, but have a 150/45 MPPT, youād still be limited to 45xV W (V depends on whether you have a 16s or 15s battery pack and how empty/full they are).
So in my case, my Pylons go to 52.4V, and I have two 150/45s, so my limit is (45+45)x52.4 = 4716W.