Victron MultiPlus II, Cerbo GX, Smartshunt, Full home back-up design

DIY
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1

Hello All,

I would like to create a home battery system which is capable for full home backup. I have some electrical knowledge but I am still a novice regarding home battery storage.

I’ve searched for some designs online but found mostly rough designs or off-grid designs so I tried to sketch up one myself.

Victron
Victron1280×720 124 KB

The goals I would like to achieve:

  • Affordable home battery system
  • Scalable (add additional storage)
  • Should be able to return to the grid after batteries are charged
  • Full home back-up
  • Use more self generated energy

Location: Netherland
The current system:

  • Grid-tied single fase with a 40A main braker (also able to sell power back to the grid)
  • 3 main groups (Green, white and PV)
  • 8 sub groups
  • SE5000h SolarEdge converter (5kW)
  • 13x 410Wp Denim panels with edge optimizers

Current idea (see image):

  • Multiplus II 48/5000 (GX)
  • Cerbo GX
  • SmartShunt 500A/50mV
  • Selector switch to exclude Victron system
  • 48v 50Ah battery with BMS

So the big question, does this design make any sense. Are there any concerns (like safety or other issues).

Hopefully someone can help me to get started.

2

The 48/5000 is not 5000 watts, it’s 5000 VA (volt amps). So it may not have as much capacity as your existing inverter.

3

You wil need way more battery for a 5000 multiplus, 2.5kW is too small

Minimum is 8kW

I suggest to contact a local victron dealer for help and system design and to keep you from expensive mistakes

as system design is not allowed here

4

When expanding, make sure +/- connections from inverter are to the opposite sides of battery array.

image
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5

Thanks for your input!

Good to know I should look for the 8000 version of the Multiplus, this would also create more room for a higher load.

Update: Done a lot more reading now. Based on
AC-coupling and the Factor 1.0 rule
chapter 2

With the 1.0 factor rule I understand you may connect a AC coupled 5000 Wp solar install to a Multiplus 48/5000 (5000 VA).

6

Thanks for the input. Would you mind elaborating a bit more?

I could not find a minimal battery size in the manual. I understand it is preferable to have a bigger capacity. But for now I would like to start with a lower cost system and increase the capacity overtime.
If there is a minimun per system size, does this also increase if I would switch to a 48/8000?

I will in the end also contact an installer but I would like to understand most of the toppic myself.

7

Noted! Thank you.

8

Look for the pylontech victron manuals,

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

its a DC system so it runs on DC, thats why you need a minimum, on a small battery the system cant even start

If you go for a 8000, you will need a bigger battery…

You also dont need an shunt with a bms battery unless the bms ia not victron compatible

If you want to understand more, read the wiring unlimited manuals, product manuals and you can also follow free victron professional trainings online

https://www.victronenergy.com/upload/documents/The_Wiring_Unlimited_book/43562-Wiring_Unlimited-pdf-en.pdf

9

Thank you for sending me the right way. I’ve done some reading about the topics and found a lot of information.

Regarding the battery size there is also an important note on how to calculate in chapter 3 of:
AC-coupling and the Factor 1.0 rule [Victron Energy]

Based on this I will need a lot more battery.

Based on your remark I also found Dyness batteries which a compatible but still affordable.