I currently run a Quattro 10 kVA system, controlled by Node-RED on a Cerbo GX. It charges a 70 kWh battery bank overnight. My off-peak window is 7 hours now and may drop to 6 or even 5. The Quattro charges at ~140 A (≈6.7 kW), which is becoming a bottleneck.
I’m considering adding a second Quattro 10 kVA for extra charging capacity and as a spare. The plan is to parallel it with the existing unit but leave the new one in charger-only mode (set via the physical switch and the VE.Bus setting). This also lets me send the original unit for repair (AC-in 2 failed within the first year).
How would control work in practice?
The documentation states that when MultiPlus/Quattro units are configured in parallel, they form a single logical inverter/charger system; inverter load and charger current are shared according to capability; and system control settings apply to the VE.Bus system as a whole, not to individual units.
If I parallel the two Quattros, set the second to charger-only, and connect to the Cerbo GX as normal, will the system automatically handle house loads/export via the original unit while the second unit contributes charging only? And if I raise the charge limit (e.g., to ~13 kW) during the off-peak window, will the charge current be shared correctly between both units?
System details: single-phase, grid-tied ESS with DVCC enabled.
This won’t work. If the 2 units are in parallel, then they must both be in the same operating state. There is no particular reason why you should not just run the 2 in parallel, they will also share the inverter load. I’ve been running 2 Multiplus units in parallel for many years with no trouble.
Ah. Trouble is I’d need g99 if I do that. I just need a charger. Maybe I’ll need a seperate cerbo and just communicate that way. Or, I haven’t checked but may be I can use an assistant and relay. It can charge at full speed and I’ll throttle on the other one.
If you just want to boost charging, you can use a server PSU for telco applications like the Eltek FlatPack2 HE, Huwai is another option. These PSUs charge up to 3kW at 98% efficiency. You get it at eBay for around 150 EUR. They can be adjusted in volatega and current ond even via custom CAN-bus message. open-source projects exist.
Hi Bjorn. Thanks for that. I am in fact running an eltek at the moment. I do get a bit concerned by the temperature of the card in the back. It’s around 60+ °c when going for it. So I have it throttle back a bit to 1.3. It’s also running from a plug at the moment which is another reason to have it powered down.
Thanks, good to know. That’ll work for me as I will just monitor what is going on and control the existing unit as required. Even with both units at maximum charge rate, it is only 0.17C on my battery bank. I only reduce the current once I hit 3.4V.
I’m thinking off doing the same but for different issues. My grid has contant brownouts.
I have a MP II 10kvas without ESS. I was thinking of buying another MPII 3kvas for example and controlling it using a relay.
Would I have some visibility on the data of that inverter on the VRM or cerbo?
I understand that the control can’t be done with the VRM but can we at least check the data for the second inverter?
I would like to have AC IN voltage and frequency for example.
I have Pylontech batteries. I simply programmed the second , “charger” MP according to the specifications for Pylontech. But without grid code and ESS assistant.
The remote console in VRM gives me the same settings and display values as for the first MP.
