I have a customer who operates a food truck who is using a 10kVA generator, a multiplus ii (48/5000/70) and 5 kWh of battery storage to supply their operations. They are experiencing issues with this as they have max spot loads of 13/14kW (total daily demand approx. 25 kWh).
They are looking to see if increased battery storage can provide the additional supply that they require. They will also need some change in their Victron system for this. A couple of questions on this:
Would it be possible to install a second Multiplus ii to operate in parallel with the existing one?
Can just one multiplus ii be connected to the generator and charge batteries?
Can both multiplus units discharge the same battery bank to enable the large spot loads to be supplied?
I don’t have experience with larger installations, but I can at least ask some clarification and others might chip in.
Is it all on one phase? That’s a lot of current if it is.
Victron produces a single phase 15kVA model, but max continuous power is 12kW and derates further when it’s hot or used at higher elevation.
Yes. But it’s advised to have a matching unit from the same year of production or as close too as possible.
Normally you have: grid/generator → Multiplus → loads. But if it is on 1 phase this is not possible as you will exceed the max input current of 50A on the 48/5000 model. The Multiplus of your client has 2 AC outputs. The first one is for critical loads. This cannot exceed the max continuous power of the Multiplus at 4000W and is powered by the batteries in case of grid/generator failure. The 2nd AC output are non critical loads and are dropped when grid/generator fails. When it is wired like this the Multiplus can help during times of heavy load. But it still can’t exceed that 50A input current limit.
Yes you can wire multiple units in parallel or 3 units in a 3 phase system. They will all be connected to one battery bank. If and how it can support peak load moments, I believe you need to wire all the loads behind the Multiplus as per point 2.
As a last thought, if your client has locations where they have grid/shore connection available, a Quattro makes an interesting choice as it can accept 2 AC inputs.
If peak demand is 14kw and you only have 15kva (theoretical) between the generator and inverter you will probably be best off with another parallel inverter (or replace with one large multiplus which isn’t as economical) Although the multiplus is rated at 5kva, they will quickly derate below this if they aren’t ventilated extremely well and any device with less than a 1.0 power factor adds to the shortage
Like mentioned, when paralleling the multiplus they have to be the exact same model, same firmware and ideally similar date codes.
As far as the battery bank is concerned, you may be able to keep what is already installed as long as it can supply the amperage at peak demand and has the capacity to handle the durations of peak demand loads. In a parallel configuration both inverters should be connected to the one common battery bank.
Im assuming these peak loads are fairly short term, and the generator is always running? As long as the generator has enough headroom to allow sufficient charging of the batteries between peak loads, it’ll work