Victron Three-Phase Home Battery Q&A

Steps

1. 1

   Step 1: Choosing the right earth leakage breaker

   Viewer peterros1798 suggested replacing the earth leakage switch in the meter box with an earth leakage circuit breaker. The part I use is an EMAT three-pole plus neutral 25A earth leakage automatic breaker.

   Viewer RichardJF3 asked why I used an EMAT breaker instead of spending extra for a more trusted brand. I have not had bad experiences with EMAT, but I am curious about your experiences and will replace it if it proves unreliable.

   What I used

   Item	Amount	Notes
   EMAT Earth Leakage Automatic Breaker	1	3-pole plus neutral, 25A

2. 2

   Step 2: Connecting the neutral wires on a distribution block

   Several viewers noted that I looped the neutral wire from one MultiPlus to the next MultiPlus. While this works, it is not the most ideal way to wire the system.

   A better method is to split the neutral wire in a distribution block and give each MultiPlus its own dedicated neutral connection. I will likely adapt this in future videos so everything uses neat distribution blocks.

3. 3

   Step 3: Using wire ferrules for connections

   Viewer jelleverhreeten7578 advised using wire ferrules when making connections with flexible cables. This is entirely correct and good advice, but I have a bad habit of first laying all the cables where they need to go and putting ferrules on them at the very end.

   If I need to change something halfway through the project, I have to cut off the ferrules and put new ones on. It is a bad habit, but it is how I did it in this video.

4. 4

   Step 4: 25A breaker and PowerAssist mode

   Viewers Weiden and Skerdebaard asked why I used a 25A installation breaker on the AC OUT since 5kVA inverters can deliver much more. It is true that the 5kVA inverters can deliver up to 40A in PowerAssist mode.

   However, our current draw does not need this, and we rarely use more than 2 to 3 kilowatts per phase. The cables between the shed and the meter box are 6 square millimetres, which can handle up to 40A, so I can upgrade the breaker later if needed.

5. 5

   Step 5: Comparing 5kVA and 3kVA MultiPlus units

   Viewers asked why I chose 5kVA MultiPlus units instead of 3kVA. The 3kVA version can load up to 35A, which on a 48V battery pack is about 1770 watts from solar to the battery pack.

   The 5kVA version can load up to 70A, which comes down to approximately 3300 watts. Since we have solar panels split across roofs and plan to add more, a 3kVA unit would not be able to store all the solar energy efficiently.

   Model	Max Load Amps	Solar Power to Battery
   3kVA	35A	1770W
   5kVA	70A	3300W

6. 6

   Step 6: Energy meters in the meter box

   MegaDreadloos asked why I did not put a Victron Energy VM-3P/75CT energy meter in the meter box. Every MultiPlus already has an energy meter built internally to measure grid power and usage.

   The only place I want an extra energy meter is at the solar panels to see how much energy comes back down from them. The MultiPlus already measures all current coming from and going to the grid.

   What I used

   Item	Amount	Notes
   Victron Energy VM-3P/75CT Energy Meter	0	Not needed in the meter box

7. 7

   Step 7: Solar panels on AC OUT

   Connecting solar panels to AC OUT lets you bridge larger distances and provides backup power during grid failures. When the grid fails, solar inverters on AC OUT continue to work and pump energy back into the battery pack.

   Current can flow in both directions: from the grid to the setup, and from the solar panels back through the MultiPlus to the batteries or grid. This makes the MultiPlus setup very flexible.

8. 8

   Step 8: Inverters versus MPPT solar chargers

   Viewers advised replacing solar inverters with MPPT solar chargers because they are more efficient. While an MPPT is more efficient than an inverter because it converts direct current to direct current directly, replacing existing inverters is not financially viable.

   The return time for replacing working inverters with MPPTs is far too long compared to the extra efficiency gained. I buy new inverters for new locations, but keep working ones.

   What I used

   Item	Amount	Notes
   MPPT Solar Charger	0	More efficient but replacement is not cost-effective

9. 9

   Step 9: Adding a bypass switch in the meter box

   Viewers berthuijgens1943, kees356, and Bart Huigens asked about adding a switch to bypass the Victron system. I added a separate small enclosure in the meter box containing only an earth leakage automatic breaker for now.

   I plan to install a proper bypass switch so I can isolate the Victron system for maintenance without cutting power to the house. This makes working on the system much safer and easier.

   What I used

   Item	Amount	Notes
   Earth leakage automatic breaker	1	Placed in an extra enclosure

10. 10

    Step 10: Emergency power and internet connections

    Toonvanderheyden asked about emergency power and internet connections. The Victron setup is already a no-break system, meaning when the grid fails, my whole house runs on battery power.

    For internet, I can use either a hardwired network cable to the Cerbo GX or connect via Wi-Fi. Both are valid options that I am considering.

11. 11

    Step 11: Handling transformer hum during phase imbalance

    Sparkelende asked about the transformer hum during phase imbalance with three MultiPlus 5000 units. During uneven loads across phases, you might hear a transformer hum.

    I plan to monitor this in future videos and add dampening plates or ventilation fans if the noise becomes too loud. Finding problems and solving them is part of the fun of DIY projects.

12. 12

    Step 12: Customizing the Lynx busbar

    I found the Victron Lynx Shunt too expensive for what it does, so I am replacing it with a SmartShunt. I will 3D print a custom housing to match the Victron look and integrate a 500A switch and a pre-charge button.

    The pre-charge button is essential because when connecting a fully discharged MultiPlus, the empty capacitors draw a massive inrush current. This rush of current can damage the BMS or create sparks at the contact points, so pre-charging protects the hardware.

    What I used

    Item	Amount	Notes
    Victron SmartShunt	1	Replaces the expensive Lynx Shunt
    500A switch	1	Used to disconnect the battery
    3D printed housing	1	Custom housing for shunt and switch

13. 13

    Step 13: Managing energy use and hobby projects

    A viewer noted that my energy use is quite high, running servers, a swimming pool pump, and 3D printers. While my household uses more energy than average due to these hobbies, I use solar power to offset it.

    Every hobby costs money, and my energy use lets me test and share these setups. I will continue sharing tips, upgrades, and lessons learned in upcoming videos.

14. 14

    Step 14: Takeaways

    • Use dedicated neutral distribution blocks for each MultiPlus unit.

    • Pre-charge capacitors to prevent massive inrush currents and protect your BMS.

    • Match your installation breaker and cable sizes to your actual power needs.

    • A bypass switch lets you safely service your inverter without cutting household power.

    • Solar panels connected to AC OUT keep your system running during grid outages.