Swopping Victron Multiplus II 3KVA for 5KVA

hi guys…

how difficult would this be… I have the one/3KVA, 5KVA is on the way…
got a quote from local guy, R7k… I"m not looking for a system to be installed, it’s pull one inverter off mountain back plate and replace with new one…

thinking the cable positions are probably all at the same place so take photo before and put cables back in same places.

I have a stand alone VRM controller… so might probable have some settings to change there…

Can then get my Sparky that recently did my CoC to come do a update on it listing the 5KVA and serial number.


Did that a long time back … you can do it.

Close as damn to plug and play.
Unscrew 6 x AC wires.
2 x battery wires.
Some data wires.

Assuming the wires at the bottom have "space to be lowered, as the 5kva is a big longer than the 3kva.

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you say 6 AC cables…

See attached

how much longer is longer


You will probably be ok…BUT - the mounting bracket may not be the same ?

2 cables consisting of a total of 6 wires inside them, AC_IN and AC_OUT. :wink:

It will fit, best to measure, the ONLY cables that may be affected are the battery cables, so what, move that box a wee bit down if you have to.

It is the same far as I could tell, between the 3kva and 5kva.

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looking at the picture, the 5kva Bracket will need to go a bit higher. The 5kva is taller then the 3kva and might end up to close to the Battery fuses. But thats drilling 3 new holes. Job should take less than 2 hours, swop out and reconfigure. 7K is a bit steep imo.


TTT if the back plate is the same, implies top point stays where it is… implies will hanger lower,
whats the length difference between the 2.

Battery wires is easy to lower, just the main blue and red that i might need to shorten.

Depending how they are fitted/connections if they straight in onto blocks then easy peasy, if they connection terminals then might need to ask my sparky to help.


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499 mm vs 565 mm, Roughly 70mm

Last 2 dimensions of the first 2 columns.

Datasheet-MultiPlus-II-inverter-charger-EN.pdf (586.4 KB)

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looks like i will be taking back board off the wall… “not totally” and have to drill new holes for new back plate,

there is about 7 cm open below current unit onto the 3 pole isolator/fuse side to side i have some space to work…


Looks easy enough … till one wants to get down to mm and it does not fit. :rofl:

THEN the job gets “bigger”, read “longer”.

When I refitted first time, from 3 to 5, I was rather upset that ALL had to be redone. We made a plan but it bothered me.

So after that fiasco, the last refit, I made space for a 10/15kva, or 2 x 5kva’s … if ever one gets there one day because of … ag sommer because of.

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I think you will be OK. 5kw will stick up over the top edge but I think if you raise the backplate right to the top of the backboard you will be fine. Send pics when done :wink:

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will do…


First hang it, or measure carefully, as rightfully pointed out, the 70mm, some may be at the top … then check if the batt cables still fit as is.

I’m a lazy oke … don’t like too much extra effort if brains can save one an hour to two.

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hindsight is always 20/20… you will see i had the original fitter leave space for a 3rd MPPT… now if we just thought about maybe replacing the 3 with a 5KVA at that time and planned for that also :wink:

Def self do-able… just see how much work it will be once i start…


biggest thing to try and get away with is try and do this without having to take everything off the wall… disconnect everything…



Physical location/space I get being fairly simple but am curious - going from 3kVA to 5kVA, will AC wire thickness and Circuit Breakers remain unchanged?

some of my logic.

The AC input is still controlled by a wire that matches the breakers on the main board, same for feeding back to the main DB, cables matches the breakers thats on that side,

but i will be getting sparky back in to update my CoC once it is done… so that will be the check again…

He did ask me last time to consider some breakers/earth leakage on my PV lines… in addition to the simple on/off breakers thats there atm.


DC cable (and fuses) to battery would be the issue for me. Rather check those spec’s.


there is 2 sets…
2 sets from 2 x PV array’s coming down… no change needed there as thats not changing.
1pair from Battery, which as it stands has a dual throw 125Amp breaker, my battery bank has always been sized bigger than the inverter… always been able to pull more than the inverter can handle before temp rising/over loading, thats why i’m upgrading inverter…

you will notice from pic… those 2 black cables and then the blue and the red are like 10mm each… they can handle anything i can even imagine generating…