Let’s say I buy two more MPIIs (48/5000/70) and configure them as a 3-phase system. Then I will switch part of the household loads to L2 and L3. But I will not be able to distribute these loads evenly and symmetrically.
Please tell me how the system of three MPIIs will behave if the following situation occurs: On output L1, a load of 3 kW is consumed, and on L2 and L3, nothing is consumed at the moment. How is the total consumption distributed by phases? Will it be balanced or will it be 3 kW - 0 - 0?
What can be done to have more energy in one phase other than using the Power Assist function?
Then I’ll only need one more MPII (on L2). In this case, should I configure it as a three-phase system (without one inverter), or as a parallel system?
So far, we haven’t had any issues with a single phase tripping. If the grid goes out, all three phases trip. So I have two questions:
Configuration Options
“I’ve decided to purchase a second inverter first. Considering I’ll have two inverters, which configuration option would you recommend? I’ve already decided to redistribute some of the household load to a separate phase/line to balance the system, meaning I’ll use L1 and L2 for now.”
Hardware and Firmware Compatibility
“Are there any risks associated with the difference in the age of the devices? I bought my first inverter almost 4 years ago, and I’m now buying a second one. Both are MultiPlus-II 48/5000/70 models.
How can I ensure that the hardware and firmware versions are fully compatible for a synchronized installation?
Here’s the information about my current equipment:”
Don’t wire your 3 phase to single. if you didn’t blow up your system immediately, you could be suppling your house with 415 Volt power, thereby blowing up your appliances and setting the house on fire. You have 3 choices as I see it.
1/ If your Multiplus has sufficient output for your needs, buy 2 chargers such as the Skylar. You could buy a second (or 3rd) Multiplus instead of the Skylars and run them in charge mode only as long as you don’t wire up the outputs. The Multiplus can run the house on Phase 1 (single phase) with excess power to the batteries, the 2nd phase runs Charger 1, 3rd phase charger 2. Charging starts immediately the power is restored with no manual intervention. This is by far the easiest, cheapest most efficient & safest way.
2/ Fully 3 phase. My advice is, unless you really need 3 phase eg running 3 phase equipment, avoid it. I had a 12 kW three phase invertor but took it out because power was limited on each phase resulting in the circuit breakers continually tripping because my wife decides to switch on a kettle and aircon and microwave at the same time. You also need to be careful to ensure the DC side is perfect with cables exactly the same length, terminations torqued the same etc. to avoid instabilities and you need to rewire your house. In practice it is very difficult to balance load across phases.
3/ The 3rd method is the way I do it and is closer to what you want, but it is complicated. I wouldn’t recommend it as there is some risk of something going wrong. I run my house (single phase) from Solar and batteries (no grid) but have a 3 phase generator during those rainy days to charge batteries. During charging, Phase One runs the house with excess power to the batteries, Phase 2 the Multiplus runs in charge mode, phase 3 runs a Skylar charger. During normal operation I run the 2 invertors in series, one as shore power. This allows me to run up to 10 kW on one phase without tripping out. (I think there has been some recent firmware changes which allows parallel operation). I installed an auto change over switch to disconnect invertor 1 AC (the one running as shore power) as soon as the 3 phase starts, to ensure I don’t have Invertor outputting power to inverter 2 while the geny is running. I have a second backup manual switch in series which I change prior to the generator starting, the automatic one being in case I forget. It works for me but I have plans to change this and buy another Skylar, charger as per option 1 and avoid using the first Multiplus as a charger. One other thing, when you have unstable power ensure you have surge protectors installed to the house and also surge protected power boards for sensitive electronic appliances. Hope this helps and good luck with your project.
I want to thank you for the comprehensive post. I really appreciate it! I read all your advice and will definitely take it into account. I also want to thank everyone else who was interested and helped me with their advice. I came to the conclusion that I need to buy a second identical inverter, install it on the second phase. This way I can simultaneously improve the power of the entire system, and speed up the charging of the batteries (due to the fact that an additional phase will be involved, i.e. +3.3 kW) and this solves the problem!
I already have two sets of branded power cables of the same length and cross-section, and I have already ordered a second inverter and additional batteries (2 so far, 4 more will be later). Thus, I will have a battery pack with a total capacity of 12 x 50 Ah. For some time I doubted whether it was possible to connect 12 such batteries at the same time without an additional low-frequency concentrator. Now I know for sure that the battery model is US2000C possible!
Now the question is: can I configure a system with two Multiplus II 48/5000/70 inverters on two phases without using the [VE.Bus to USB] interface (since I don’t have it). If so, please tell me what are the main steps I need to take. There are many programs for configuring Victron systems, but which one should I use?
Sorry for the questions that may have already been discussed here before.
And I still haven’t found a single mention of the Skylar charger…
When downloading a config for complex systems, the workflow changes. You’ll need to use VE.Bus Quick Configure to assign roles to each inverter. From there, you can right-click each unit to access VE.Configure 3 for individual settings.
While you can attempt this via Remote VE.Configure (without an MK3-USB), it’s risky if the connection drops. If you get stuck, check the Ukrainian Victron Telegram group—someone there will likely have a spare cable to lend you.
Also, make sure that the firmware on all inverters is identical.
