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Elimac avatar image
Elimac asked

Two Multiplus inverters - best aproach?

I have a Multiplus 3000/24/70. I have the chance to get a 2000/24/50 from a friend. But I'm wondering about the possibilities to really use it... I would like some backup (emergency) for my single inverter. I'm ruling out parallel operation, since they are different models. So, what could be the best approach?


1- Connected to same battery bank and split phase operation. Divide AC loads among the two. Arises one question... I would like to keep charging at night with my main Inverter (3kVa), changing operation from Inverter to Charger. Can they both change mode at same time and disable the charger of the 2kva inverter? This one would only be in pass trough (AC in/out) during off-peak tariff period.


2- Connected to two different/ independent battery banks and connected in cascade mode (first would be 2kva and 2nd would be 3kva, more close to the loads). Take advantage of power assist and centralizing the loads on the 3000VA inverter. In order to charge from AC on the main bank, I would need to put the 2kva inverter in passtrough, to avoid draining one battery bank into the other...


3-Connected to different battery banks and split the loads. Two separate systems. I guess would be the easiest and less confuse way to take advantage of the two devices.




MultiPlus Quattro Inverter Chargersplit phase
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3 Answers
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wkirby answered ·

So you cannot pair them in any way what so ever on the AC-OUT side nor on the same VE.Bus, like you say, they are different models.

You can connect them to the same battery bank and have separate independant AC loads on each one. I'd have the 3KVA assigned to charging at night as it's got a more powerful charger but the 2KVA would keep inverting.
If both AC-IN were connected to the supply then they would both charge the battery bank, but I wouldn't like to have two independant chargers on the same bank. Even if the charging parameters were identical on both machines, there would still be some anomolies between the two and it may cause some problems.

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Elimac avatar image
Elimac answered ·

Thanks for reply. Yes, I agree with you - would prefer to use just one inverter to charge the battery (the 3kva one). But I was convinced I could connect both inverters to same VE.Bus, (independent AC out or in split phase) and controlled by same Venus device. This way, I would try to make them switch between Inverter and charger at same time, but disable the charger (current = 0) in one of them. Isn't this possible?

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ben avatar image ben ♦ commented ·

Just a small clarification: "split phase" and "independent" are not the same. You can't put two different inverters into a split phase configuration, because achieving split phase requires them to synchronize their waveforms.

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wkirby answered ·

OK, so I didn't realise that you had a Venus device. This may open up some opportinities for instructing the 2KVA MultiPlus to track what the 3KVA one is doing, but then I really don't know how a Venus device would respond to two VE.Bus instances, I have never tried this.

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Stan Flowers avatar image Stan Flowers commented ·
Hi, this is an interesting discussion thanks. would this also work for say, a setup where a continuous power supply is needed 24/7 and the 2nd inverter ( assuming the same as the 1st, i.e. both 3kva) acts as a stanby backup inverter to the 1st. If or when the first unit fails the second is brought in in a UPS type mode to supply the loads, until the 1st is repaired or replaced. Can programmable relays be used to make this happen, with an auto transfer switch?
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